/* ** 2001 September 15 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This file contains C code routines that are called by the parser ** to handle SELECT statements in SQLite. */ #include "sqliteInt.h" /* ** Trace output macros */ #if SELECTTRACE_ENABLED /***/ int sqlite3SelectTrace = 0; # define SELECTTRACE(K,P,S,X) \ if(sqlite3SelectTrace&(K)) \ sqlite3DebugPrintf("%*s%s.%p: ",(P)->nSelectIndent*2-2,"",\ (S)->zSelName,(S)),\ sqlite3DebugPrintf X #else # define SELECTTRACE(K,P,S,X) #endif /* ** An instance of the following object is used to record information about ** how to process the DISTINCT keyword, to simplify passing that information ** into the selectInnerLoop() routine. */ typedef struct DistinctCtx DistinctCtx; struct DistinctCtx { u8 isTnct; /* True if the DISTINCT keyword is present */ u8 eTnctType; /* One of the WHERE_DISTINCT_* operators */ int tabTnct; /* Ephemeral table used for DISTINCT processing */ int addrTnct; /* Address of OP_OpenEphemeral opcode for tabTnct */ }; /* ** An instance of the following object is used to record information about ** the ORDER BY (or GROUP BY) clause of query is being coded. */ typedef struct SortCtx SortCtx; struct SortCtx { ExprList *pOrderBy; /* The ORDER BY (or GROUP BY clause) */ int nOBSat; /* Number of ORDER BY terms satisfied by indices */ int iECursor; /* Cursor number for the sorter */ int regReturn; /* Register holding block-output return address */ int labelBkOut; /* Start label for the block-output subroutine */ int addrSortIndex; /* Address of the OP_SorterOpen or OP_OpenEphemeral */ int labelDone; /* Jump here when done, ex: LIMIT reached */ u8 sortFlags; /* Zero or more SORTFLAG_* bits */ u8 bOrderedInnerLoop; /* ORDER BY correctly sorts the inner loop */ }; #define SORTFLAG_UseSorter 0x01 /* Use SorterOpen instead of OpenEphemeral */ /* ** Delete all the content of a Select structure. Deallocate the structure ** itself only if bFree is true. */ static void clearSelect(sqlite3 *db, Select *p, int bFree){ while( p ){ Select *pPrior = p->pPrior; sqlite3ExprListDelete(db, p->pEList); sqlite3SrcListDelete(db, p->pSrc); sqlite3ExprDelete(db, p->pWhere); sqlite3ExprListDelete(db, p->pGroupBy); sqlite3ExprDelete(db, p->pHaving); sqlite3ExprListDelete(db, p->pOrderBy); sqlite3ExprDelete(db, p->pLimit); sqlite3ExprDelete(db, p->pOffset); if( p->pWith ) sqlite3WithDelete(db, p->pWith); if( bFree ) sqlite3DbFree(db, p); p = pPrior; bFree = 1; } } /* ** Initialize a SelectDest structure. */ void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){ pDest->eDest = (u8)eDest; pDest->iSDParm = iParm; pDest->zAffSdst = 0; pDest->iSdst = 0; pDest->nSdst = 0; } /* ** Allocate a new Select structure and return a pointer to that ** structure. */ Select *sqlite3SelectNew( Parse *pParse, /* Parsing context */ ExprList *pEList, /* which columns to include in the result */ SrcList *pSrc, /* the FROM clause -- which tables to scan */ Expr *pWhere, /* the WHERE clause */ ExprList *pGroupBy, /* the GROUP BY clause */ Expr *pHaving, /* the HAVING clause */ ExprList *pOrderBy, /* the ORDER BY clause */ u32 selFlags, /* Flag parameters, such as SF_Distinct */ Expr *pLimit, /* LIMIT value. NULL means not used */ Expr *pOffset /* OFFSET value. NULL means no offset */ ){ Select *pNew; Select standin; sqlite3 *db = pParse->db; pNew = sqlite3DbMallocRawNN(db, sizeof(*pNew) ); if( pNew==0 ){ assert( db->mallocFailed ); pNew = &standin; } if( pEList==0 ){ pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ASTERISK,0)); } pNew->pEList = pEList; pNew->op = TK_SELECT; pNew->selFlags = selFlags; pNew->iLimit = 0; pNew->iOffset = 0; #if SELECTTRACE_ENABLED pNew->zSelName[0] = 0; #endif pNew->addrOpenEphm[0] = -1; pNew->addrOpenEphm[1] = -1; pNew->nSelectRow = 0; if( pSrc==0 ) pSrc = sqlite3DbMallocZero(db, sizeof(*pSrc)); pNew->pSrc = pSrc; pNew->pWhere = pWhere; pNew->pGroupBy = pGroupBy; pNew->pHaving = pHaving; pNew->pOrderBy = pOrderBy; pNew->pPrior = 0; pNew->pNext = 0; pNew->pLimit = pLimit; pNew->pOffset = pOffset; pNew->pWith = 0; assert( pOffset==0 || pLimit!=0 || pParse->nErr>0 || db->mallocFailed!=0 ); if( db->mallocFailed ) { clearSelect(db, pNew, pNew!=&standin); pNew = 0; }else{ assert( pNew->pSrc!=0 || pParse->nErr>0 ); } assert( pNew!=&standin ); return pNew; } #if SELECTTRACE_ENABLED /* ** Set the name of a Select object */ void sqlite3SelectSetName(Select *p, const char *zName){ if( p && zName ){ sqlite3_snprintf(sizeof(p->zSelName), p->zSelName, "%s", zName); } } #endif /* ** Delete the given Select structure and all of its substructures. */ void sqlite3SelectDelete(sqlite3 *db, Select *p){ if( p ) clearSelect(db, p, 1); } /* ** Return a pointer to the right-most SELECT statement in a compound. */ static Select *findRightmost(Select *p){ while( p->pNext ) p = p->pNext; return p; } /* ** Given 1 to 3 identifiers preceding the JOIN keyword, determine the ** type of join. Return an integer constant that expresses that type ** in terms of the following bit values: ** ** JT_INNER ** JT_CROSS ** JT_OUTER ** JT_NATURAL ** JT_LEFT ** JT_RIGHT ** ** A full outer join is the combination of JT_LEFT and JT_RIGHT. ** ** If an illegal or unsupported join type is seen, then still return ** a join type, but put an error in the pParse structure. */ int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){ int jointype = 0; Token *apAll[3]; Token *p; /* 0123456789 123456789 123456789 123 */ static const char zKeyText[] = "naturaleftouterightfullinnercross"; static const struct { u8 i; /* Beginning of keyword text in zKeyText[] */ u8 nChar; /* Length of the keyword in characters */ u8 code; /* Join type mask */ } aKeyword[] = { /* natural */ { 0, 7, JT_NATURAL }, /* left */ { 6, 4, JT_LEFT|JT_OUTER }, /* outer */ { 10, 5, JT_OUTER }, /* right */ { 14, 5, JT_RIGHT|JT_OUTER }, /* full */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER }, /* inner */ { 23, 5, JT_INNER }, /* cross */ { 28, 5, JT_INNER|JT_CROSS }, }; int i, j; apAll[0] = pA; apAll[1] = pB; apAll[2] = pC; for(i=0; i<3 && apAll[i]; i++){ p = apAll[i]; for(j=0; jn==aKeyword[j].nChar && sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){ jointype |= aKeyword[j].code; break; } } testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 ); if( j>=ArraySize(aKeyword) ){ jointype |= JT_ERROR; break; } } if( (jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) || (jointype & JT_ERROR)!=0 ){ const char *zSp = " "; assert( pB!=0 ); if( pC==0 ){ zSp++; } sqlite3ErrorMsg(pParse, "unknown or unsupported join type: " "%T %T%s%T", pA, pB, zSp, pC); jointype = JT_INNER; }else if( (jointype & JT_OUTER)!=0 && (jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ){ sqlite3ErrorMsg(pParse, "RIGHT and FULL OUTER JOINs are not currently supported"); jointype = JT_INNER; } return jointype; } /* ** Return the index of a column in a table. Return -1 if the column ** is not contained in the table. */ static int columnIndex(Table *pTab, const char *zCol){ int i; for(i=0; inCol; i++){ if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i; } return -1; } /* ** Search the first N tables in pSrc, from left to right, looking for a ** table that has a column named zCol. ** ** When found, set *piTab and *piCol to the table index and column index ** of the matching column and return TRUE. ** ** If not found, return FALSE. */ static int tableAndColumnIndex( SrcList *pSrc, /* Array of tables to search */ int N, /* Number of tables in pSrc->a[] to search */ const char *zCol, /* Name of the column we are looking for */ int *piTab, /* Write index of pSrc->a[] here */ int *piCol /* Write index of pSrc->a[*piTab].pTab->aCol[] here */ ){ int i; /* For looping over tables in pSrc */ int iCol; /* Index of column matching zCol */ assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */ for(i=0; ia[i].pTab, zCol); if( iCol>=0 ){ if( piTab ){ *piTab = i; *piCol = iCol; } return 1; } } return 0; } /* ** This function is used to add terms implied by JOIN syntax to the ** WHERE clause expression of a SELECT statement. The new term, which ** is ANDed with the existing WHERE clause, is of the form: ** ** (tab1.col1 = tab2.col2) ** ** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the ** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is ** column iColRight of tab2. */ static void addWhereTerm( Parse *pParse, /* Parsing context */ SrcList *pSrc, /* List of tables in FROM clause */ int iLeft, /* Index of first table to join in pSrc */ int iColLeft, /* Index of column in first table */ int iRight, /* Index of second table in pSrc */ int iColRight, /* Index of column in second table */ int isOuterJoin, /* True if this is an OUTER join */ Expr **ppWhere /* IN/OUT: The WHERE clause to add to */ ){ sqlite3 *db = pParse->db; Expr *pE1; Expr *pE2; Expr *pEq; assert( iLeftnSrc>iRight ); assert( pSrc->a[iLeft].pTab ); assert( pSrc->a[iRight].pTab ); pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iColLeft); pE2 = sqlite3CreateColumnExpr(db, pSrc, iRight, iColRight); pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2, 0); if( pEq && isOuterJoin ){ ExprSetProperty(pEq, EP_FromJoin); assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) ); ExprSetVVAProperty(pEq, EP_NoReduce); pEq->iRightJoinTable = (i16)pE2->iTable; } *ppWhere = sqlite3ExprAnd(db, *ppWhere, pEq); } /* ** Set the EP_FromJoin property on all terms of the given expression. ** And set the Expr.iRightJoinTable to iTable for every term in the ** expression. ** ** The EP_FromJoin property is used on terms of an expression to tell ** the LEFT OUTER JOIN processing logic that this term is part of the ** join restriction specified in the ON or USING clause and not a part ** of the more general WHERE clause. These terms are moved over to the ** WHERE clause during join processing but we need to remember that they ** originated in the ON or USING clause. ** ** The Expr.iRightJoinTable tells the WHERE clause processing that the ** expression depends on table iRightJoinTable even if that table is not ** explicitly mentioned in the expression. That information is needed ** for cases like this: ** ** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5 ** ** The where clause needs to defer the handling of the t1.x=5 ** term until after the t2 loop of the join. In that way, a ** NULL t2 row will be inserted whenever t1.x!=5. If we do not ** defer the handling of t1.x=5, it will be processed immediately ** after the t1 loop and rows with t1.x!=5 will never appear in ** the output, which is incorrect. */ static void setJoinExpr(Expr *p, int iTable){ while( p ){ ExprSetProperty(p, EP_FromJoin); assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) ); ExprSetVVAProperty(p, EP_NoReduce); p->iRightJoinTable = (i16)iTable; if( p->op==TK_FUNCTION && p->x.pList ){ int i; for(i=0; ix.pList->nExpr; i++){ setJoinExpr(p->x.pList->a[i].pExpr, iTable); } } setJoinExpr(p->pLeft, iTable); p = p->pRight; } } /* ** This routine processes the join information for a SELECT statement. ** ON and USING clauses are converted into extra terms of the WHERE clause. ** NATURAL joins also create extra WHERE clause terms. ** ** The terms of a FROM clause are contained in the Select.pSrc structure. ** The left most table is the first entry in Select.pSrc. The right-most ** table is the last entry. The join operator is held in the entry to ** the left. Thus entry 0 contains the join operator for the join between ** entries 0 and 1. Any ON or USING clauses associated with the join are ** also attached to the left entry. ** ** This routine returns the number of errors encountered. */ static int sqliteProcessJoin(Parse *pParse, Select *p){ SrcList *pSrc; /* All tables in the FROM clause */ int i, j; /* Loop counters */ struct SrcList_item *pLeft; /* Left table being joined */ struct SrcList_item *pRight; /* Right table being joined */ pSrc = p->pSrc; pLeft = &pSrc->a[0]; pRight = &pLeft[1]; for(i=0; inSrc-1; i++, pRight++, pLeft++){ Table *pLeftTab = pLeft->pTab; Table *pRightTab = pRight->pTab; int isOuter; if( NEVER(pLeftTab==0 || pRightTab==0) ) continue; isOuter = (pRight->fg.jointype & JT_OUTER)!=0; /* When the NATURAL keyword is present, add WHERE clause terms for ** every column that the two tables have in common. */ if( pRight->fg.jointype & JT_NATURAL ){ if( pRight->pOn || pRight->pUsing ){ sqlite3ErrorMsg(pParse, "a NATURAL join may not have " "an ON or USING clause", 0); return 1; } for(j=0; jnCol; j++){ char *zName; /* Name of column in the right table */ int iLeft; /* Matching left table */ int iLeftCol; /* Matching column in the left table */ zName = pRightTab->aCol[j].zName; if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){ addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j, isOuter, &p->pWhere); } } } /* Disallow both ON and USING clauses in the same join */ if( pRight->pOn && pRight->pUsing ){ sqlite3ErrorMsg(pParse, "cannot have both ON and USING " "clauses in the same join"); return 1; } /* Add the ON clause to the end of the WHERE clause, connected by ** an AND operator. */ if( pRight->pOn ){ if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor); p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn); pRight->pOn = 0; } /* Create extra terms on the WHERE clause for each column named ** in the USING clause. Example: If the two tables to be joined are ** A and B and the USING clause names X, Y, and Z, then add this ** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z ** Report an error if any column mentioned in the USING clause is ** not contained in both tables to be joined. */ if( pRight->pUsing ){ IdList *pList = pRight->pUsing; for(j=0; jnId; j++){ char *zName; /* Name of the term in the USING clause */ int iLeft; /* Table on the left with matching column name */ int iLeftCol; /* Column number of matching column on the left */ int iRightCol; /* Column number of matching column on the right */ zName = pList->a[j].zName; iRightCol = columnIndex(pRightTab, zName); if( iRightCol<0 || !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){ sqlite3ErrorMsg(pParse, "cannot join using column %s - column " "not present in both tables", zName); return 1; } addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol, isOuter, &p->pWhere); } } } return 0; } /* Forward reference */ static KeyInfo *keyInfoFromExprList( Parse *pParse, /* Parsing context */ ExprList *pList, /* Form the KeyInfo object from this ExprList */ int iStart, /* Begin with this column of pList */ int nExtra /* Add this many extra columns to the end */ ); /* ** Generate code that will push the record in registers regData ** through regData+nData-1 onto the sorter. */ static void pushOntoSorter( Parse *pParse, /* Parser context */ SortCtx *pSort, /* Information about the ORDER BY clause */ Select *pSelect, /* The whole SELECT statement */ int regData, /* First register holding data to be sorted */ int regOrigData, /* First register holding data before packing */ int nData, /* Number of elements in the data array */ int nPrefixReg /* No. of reg prior to regData available for use */ ){ Vdbe *v = pParse->pVdbe; /* Stmt under construction */ int bSeq = ((pSort->sortFlags & SORTFLAG_UseSorter)==0); int nExpr = pSort->pOrderBy->nExpr; /* No. of ORDER BY terms */ int nBase = nExpr + bSeq + nData; /* Fields in sorter record */ int regBase; /* Regs for sorter record */ int regRecord = ++pParse->nMem; /* Assembled sorter record */ int nOBSat = pSort->nOBSat; /* ORDER BY terms to skip */ int op; /* Opcode to add sorter record to sorter */ int iLimit; /* LIMIT counter */ assert( bSeq==0 || bSeq==1 ); assert( nData==1 || regData==regOrigData ); if( nPrefixReg ){ assert( nPrefixReg==nExpr+bSeq ); regBase = regData - nExpr - bSeq; }else{ regBase = pParse->nMem + 1; pParse->nMem += nBase; } assert( pSelect->iOffset==0 || pSelect->iLimit!=0 ); iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit; pSort->labelDone = sqlite3VdbeMakeLabel(v); sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData, SQLITE_ECEL_DUP|SQLITE_ECEL_REF); if( bSeq ){ sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr); } if( nPrefixReg==0 ){ sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData); } sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regRecord); if( nOBSat>0 ){ int regPrevKey; /* The first nOBSat columns of the previous row */ int addrFirst; /* Address of the OP_IfNot opcode */ int addrJmp; /* Address of the OP_Jump opcode */ VdbeOp *pOp; /* Opcode that opens the sorter */ int nKey; /* Number of sorting key columns, including OP_Sequence */ KeyInfo *pKI; /* Original KeyInfo on the sorter table */ regPrevKey = pParse->nMem+1; pParse->nMem += pSort->nOBSat; nKey = nExpr - pSort->nOBSat + bSeq; if( bSeq ){ addrFirst = sqlite3VdbeAddOp1(v, OP_IfNot, regBase+nExpr); }else{ addrFirst = sqlite3VdbeAddOp1(v, OP_SequenceTest, pSort->iECursor); } VdbeCoverage(v); sqlite3VdbeAddOp3(v, OP_Compare, regPrevKey, regBase, pSort->nOBSat); pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex); if( pParse->db->mallocFailed ) return; pOp->p2 = nKey + nData; pKI = pOp->p4.pKeyInfo; memset(pKI->aSortOrder, 0, pKI->nField); /* Makes OP_Jump below testable */ sqlite3VdbeChangeP4(v, -1, (char*)pKI, P4_KEYINFO); testcase( pKI->nXField>2 ); pOp->p4.pKeyInfo = keyInfoFromExprList(pParse, pSort->pOrderBy, nOBSat, pKI->nXField-1); addrJmp = sqlite3VdbeCurrentAddr(v); sqlite3VdbeAddOp3(v, OP_Jump, addrJmp+1, 0, addrJmp+1); VdbeCoverage(v); pSort->labelBkOut = sqlite3VdbeMakeLabel(v); pSort->regReturn = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut); sqlite3VdbeAddOp1(v, OP_ResetSorter, pSort->iECursor); if( iLimit ){ sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, pSort->labelDone); VdbeCoverage(v); } sqlite3VdbeJumpHere(v, addrFirst); sqlite3ExprCodeMove(pParse, regBase, regPrevKey, pSort->nOBSat); sqlite3VdbeJumpHere(v, addrJmp); } if( pSort->sortFlags & SORTFLAG_UseSorter ){ op = OP_SorterInsert; }else{ op = OP_IdxInsert; } sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord); if( iLimit ){ int addr; int r1 = 0; /* Fill the sorter until it contains LIMIT+OFFSET entries. (The iLimit ** register is initialized with value of LIMIT+OFFSET.) After the sorter ** fills up, delete the least entry in the sorter after each insert. ** Thus we never hold more than the LIMIT+OFFSET rows in memory at once */ addr = sqlite3VdbeAddOp3(v, OP_IfNotZero, iLimit, 0, 1); VdbeCoverage(v); sqlite3VdbeAddOp1(v, OP_Last, pSort->iECursor); if( pSort->bOrderedInnerLoop ){ r1 = ++pParse->nMem; sqlite3VdbeAddOp3(v, OP_Column, pSort->iECursor, nExpr, r1); VdbeComment((v, "seq")); } sqlite3VdbeAddOp1(v, OP_Delete, pSort->iECursor); if( pSort->bOrderedInnerLoop ){ /* If the inner loop is driven by an index such that values from ** the same iteration of the inner loop are in sorted order, then ** immediately jump to the next iteration of an inner loop if the ** entry from the current iteration does not fit into the top ** LIMIT+OFFSET entries of the sorter. */ int iBrk = sqlite3VdbeCurrentAddr(v) + 2; sqlite3VdbeAddOp3(v, OP_Eq, regBase+nExpr, iBrk, r1); sqlite3VdbeChangeP5(v, SQLITE_NULLEQ); VdbeCoverage(v); } sqlite3VdbeJumpHere(v, addr); } } /* ** Add code to implement the OFFSET */ static void codeOffset( Vdbe *v, /* Generate code into this VM */ int iOffset, /* Register holding the offset counter */ int iContinue /* Jump here to skip the current record */ ){ if( iOffset>0 ){ sqlite3VdbeAddOp3(v, OP_IfPos, iOffset, iContinue, 1); VdbeCoverage(v); VdbeComment((v, "OFFSET")); } } /* ** Add code that will check to make sure the N registers starting at iMem ** form a distinct entry. iTab is a sorting index that holds previously ** seen combinations of the N values. A new entry is made in iTab ** if the current N values are new. ** ** A jump to addrRepeat is made and the N+1 values are popped from the ** stack if the top N elements are not distinct. */ static void codeDistinct( Parse *pParse, /* Parsing and code generating context */ int iTab, /* A sorting index used to test for distinctness */ int addrRepeat, /* Jump to here if not distinct */ int N, /* Number of elements */ int iMem /* First element */ ){ Vdbe *v; int r1; v = pParse->pVdbe; r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N); VdbeCoverage(v); sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1); sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1); sqlite3ReleaseTempReg(pParse, r1); } /* ** This routine generates the code for the inside of the inner loop ** of a SELECT. ** ** If srcTab is negative, then the pEList expressions ** are evaluated in order to get the data for this row. If srcTab is ** zero or more, then data is pulled from srcTab and pEList is used only ** to get number columns and the datatype for each column. */ static void selectInnerLoop( Parse *pParse, /* The parser context */ Select *p, /* The complete select statement being coded */ ExprList *pEList, /* List of values being extracted */ int srcTab, /* Pull data from this table */ SortCtx *pSort, /* If not NULL, info on how to process ORDER BY */ DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */ SelectDest *pDest, /* How to dispose of the results */ int iContinue, /* Jump here to continue with next row */ int iBreak /* Jump here to break out of the inner loop */ ){ Vdbe *v = pParse->pVdbe; int i; int hasDistinct; /* True if the DISTINCT keyword is present */ int regResult; /* Start of memory holding result set */ int eDest = pDest->eDest; /* How to dispose of results */ int iParm = pDest->iSDParm; /* First argument to disposal method */ int nResultCol; /* Number of result columns */ int nPrefixReg = 0; /* Number of extra registers before regResult */ assert( v ); assert( pEList!=0 ); hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP; if( pSort && pSort->pOrderBy==0 ) pSort = 0; if( pSort==0 && !hasDistinct ){ assert( iContinue!=0 ); codeOffset(v, p->iOffset, iContinue); } /* Pull the requested columns. */ nResultCol = pEList->nExpr; if( pDest->iSdst==0 ){ if( pSort ){ nPrefixReg = pSort->pOrderBy->nExpr; if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++; pParse->nMem += nPrefixReg; } pDest->iSdst = pParse->nMem+1; pParse->nMem += nResultCol; }else if( pDest->iSdst+nResultCol > pParse->nMem ){ /* This is an error condition that can result, for example, when a SELECT ** on the right-hand side of an INSERT contains more result columns than ** there are columns in the table on the left. The error will be caught ** and reported later. But we need to make sure enough memory is allocated ** to avoid other spurious errors in the meantime. */ pParse->nMem += nResultCol; } pDest->nSdst = nResultCol; regResult = pDest->iSdst; if( srcTab>=0 ){ for(i=0; ia[i].zName)); } }else if( eDest!=SRT_Exists ){ /* If the destination is an EXISTS(...) expression, the actual ** values returned by the SELECT are not required. */ u8 ecelFlags; if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){ ecelFlags = SQLITE_ECEL_DUP; }else{ ecelFlags = 0; } sqlite3ExprCodeExprList(pParse, pEList, regResult, 0, ecelFlags); } /* If the DISTINCT keyword was present on the SELECT statement ** and this row has been seen before, then do not make this row ** part of the result. */ if( hasDistinct ){ switch( pDistinct->eTnctType ){ case WHERE_DISTINCT_ORDERED: { VdbeOp *pOp; /* No longer required OpenEphemeral instr. */ int iJump; /* Jump destination */ int regPrev; /* Previous row content */ /* Allocate space for the previous row */ regPrev = pParse->nMem+1; pParse->nMem += nResultCol; /* Change the OP_OpenEphemeral coded earlier to an OP_Null ** sets the MEM_Cleared bit on the first register of the ** previous value. This will cause the OP_Ne below to always ** fail on the first iteration of the loop even if the first ** row is all NULLs. */ sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct); pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct); pOp->opcode = OP_Null; pOp->p1 = 1; pOp->p2 = regPrev; iJump = sqlite3VdbeCurrentAddr(v) + nResultCol; for(i=0; ia[i].pExpr); if( idb->mallocFailed ); sqlite3VdbeAddOp3(v, OP_Copy, regResult, regPrev, nResultCol-1); break; } case WHERE_DISTINCT_UNIQUE: { sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct); break; } default: { assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED ); codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol, regResult); break; } } if( pSort==0 ){ codeOffset(v, p->iOffset, iContinue); } } switch( eDest ){ /* In this mode, write each query result to the key of the temporary ** table iParm. */ #ifndef SQLITE_OMIT_COMPOUND_SELECT case SRT_Union: { int r1; r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); sqlite3ReleaseTempReg(pParse, r1); break; } /* Construct a record from the query result, but instead of ** saving that record, use it as a key to delete elements from ** the temporary table iParm. */ case SRT_Except: { sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nResultCol); break; } #endif /* SQLITE_OMIT_COMPOUND_SELECT */ /* Store the result as data using a unique key. */ case SRT_Fifo: case SRT_DistFifo: case SRT_Table: case SRT_EphemTab: { int r1 = sqlite3GetTempRange(pParse, nPrefixReg+1); testcase( eDest==SRT_Table ); testcase( eDest==SRT_EphemTab ); testcase( eDest==SRT_Fifo ); testcase( eDest==SRT_DistFifo ); sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1+nPrefixReg); #ifndef SQLITE_OMIT_CTE if( eDest==SRT_DistFifo ){ /* If the destination is DistFifo, then cursor (iParm+1) is open ** on an ephemeral index. If the current row is already present ** in the index, do not write it to the output. If not, add the ** current row to the index and proceed with writing it to the ** output table as well. */ int addr = sqlite3VdbeCurrentAddr(v) + 4; sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0); VdbeCoverage(v); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1); assert( pSort==0 ); } #endif if( pSort ){ pushOntoSorter(pParse, pSort, p, r1+nPrefixReg,regResult,1,nPrefixReg); }else{ int r2 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2); sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2); sqlite3VdbeChangeP5(v, OPFLAG_APPEND); sqlite3ReleaseTempReg(pParse, r2); } sqlite3ReleaseTempRange(pParse, r1, nPrefixReg+1); break; } #ifndef SQLITE_OMIT_SUBQUERY /* If we are creating a set for an "expr IN (SELECT ...)" construct, ** then there should be a single item on the stack. Write this ** item into the set table with bogus data. */ case SRT_Set: { if( pSort ){ /* At first glance you would think we could optimize out the ** ORDER BY in this case since the order of entries in the set ** does not matter. But there might be a LIMIT clause, in which ** case the order does matter */ pushOntoSorter( pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg); }else{ int r1 = sqlite3GetTempReg(pParse); assert( sqlite3Strlen30(pDest->zAffSdst)==nResultCol ); sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, nResultCol, r1, pDest->zAffSdst, nResultCol); sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); sqlite3ReleaseTempReg(pParse, r1); } break; } /* If any row exist in the result set, record that fact and abort. */ case SRT_Exists: { sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm); /* The LIMIT clause will terminate the loop for us */ break; } /* If this is a scalar select that is part of an expression, then ** store the results in the appropriate memory cell or array of ** memory cells and break out of the scan loop. */ case SRT_Mem: { assert( nResultCol==pDest->nSdst ); if( pSort ){ pushOntoSorter( pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg); }else{ assert( regResult==iParm ); /* The LIMIT clause will jump out of the loop for us */ } break; } #endif /* #ifndef SQLITE_OMIT_SUBQUERY */ case SRT_Coroutine: /* Send data to a co-routine */ case SRT_Output: { /* Return the results */ testcase( eDest==SRT_Coroutine ); testcase( eDest==SRT_Output ); if( pSort ){ pushOntoSorter(pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg); }else if( eDest==SRT_Coroutine ){ sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm); }else{ sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol); sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol); } break; } #ifndef SQLITE_OMIT_CTE /* Write the results into a priority queue that is order according to ** pDest->pOrderBy (in pSO). pDest->iSDParm (in iParm) is the cursor for an ** index with pSO->nExpr+2 columns. Build a key using pSO for the first ** pSO->nExpr columns, then make sure all keys are unique by adding a ** final OP_Sequence column. The last column is the record as a blob. */ case SRT_DistQueue: case SRT_Queue: { int nKey; int r1, r2, r3; int addrTest = 0; ExprList *pSO; pSO = pDest->pOrderBy; assert( pSO ); nKey = pSO->nExpr; r1 = sqlite3GetTempReg(pParse); r2 = sqlite3GetTempRange(pParse, nKey+2); r3 = r2+nKey+1; if( eDest==SRT_DistQueue ){ /* If the destination is DistQueue, then cursor (iParm+1) is open ** on a second ephemeral index that holds all values every previously ** added to the queue. */ addrTest = sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, 0, regResult, nResultCol); VdbeCoverage(v); } sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r3); if( eDest==SRT_DistQueue ){ sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r3); sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT); } for(i=0; ia[i].u.x.iOrderByCol - 1, r2+i); } sqlite3VdbeAddOp2(v, OP_Sequence, iParm, r2+nKey); sqlite3VdbeAddOp3(v, OP_MakeRecord, r2, nKey+2, r1); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); if( addrTest ) sqlite3VdbeJumpHere(v, addrTest); sqlite3ReleaseTempReg(pParse, r1); sqlite3ReleaseTempRange(pParse, r2, nKey+2); break; } #endif /* SQLITE_OMIT_CTE */ #if !defined(SQLITE_OMIT_TRIGGER) /* Discard the results. This is used for SELECT statements inside ** the body of a TRIGGER. The purpose of such selects is to call ** user-defined functions that have side effects. We do not care ** about the actual results of the select. */ default: { assert( eDest==SRT_Discard ); break; } #endif } /* Jump to the end of the loop if the LIMIT is reached. Except, if ** there is a sorter, in which case the sorter has already limited ** the output for us. */ if( pSort==0 && p->iLimit ){ sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v); } } /* ** Allocate a KeyInfo object sufficient for an index of N key columns and ** X extra columns. */ KeyInfo *sqlite3KeyInfoAlloc(sqlite3 *db, int N, int X){ int nExtra = (N+X)*(sizeof(CollSeq*)+1); KeyInfo *p = sqlite3DbMallocRaw(db, sizeof(KeyInfo) + nExtra); if( p ){ p->aSortOrder = (u8*)&p->aColl[N+X]; p->nField = (u16)N; p->nXField = (u16)X; p->enc = ENC(db); p->db = db; p->nRef = 1; memset(&p[1], 0, nExtra); }else{ sqlite3OomFault(db); } return p; } /* ** Deallocate a KeyInfo object */ void sqlite3KeyInfoUnref(KeyInfo *p){ if( p ){ assert( p->nRef>0 ); p->nRef--; if( p->nRef==0 ) sqlite3DbFree(p->db, p); } } /* ** Make a new pointer to a KeyInfo object */ KeyInfo *sqlite3KeyInfoRef(KeyInfo *p){ if( p ){ assert( p->nRef>0 ); p->nRef++; } return p; } #ifdef SQLITE_DEBUG /* ** Return TRUE if a KeyInfo object can be change. The KeyInfo object ** can only be changed if this is just a single reference to the object. ** ** This routine is used only inside of assert() statements. */ int sqlite3KeyInfoIsWriteable(KeyInfo *p){ return p->nRef==1; } #endif /* SQLITE_DEBUG */ /* ** Given an expression list, generate a KeyInfo structure that records ** the collating sequence for each expression in that expression list. ** ** If the ExprList is an ORDER BY or GROUP BY clause then the resulting ** KeyInfo structure is appropriate for initializing a virtual index to ** implement that clause. If the ExprList is the result set of a SELECT ** then the KeyInfo structure is appropriate for initializing a virtual ** index to implement a DISTINCT test. ** ** Space to hold the KeyInfo structure is obtained from malloc. The calling ** function is responsible for seeing that this structure is eventually ** freed. */ static KeyInfo *keyInfoFromExprList( Parse *pParse, /* Parsing context */ ExprList *pList, /* Form the KeyInfo object from this ExprList */ int iStart, /* Begin with this column of pList */ int nExtra /* Add this many extra columns to the end */ ){ int nExpr; KeyInfo *pInfo; struct ExprList_item *pItem; sqlite3 *db = pParse->db; int i; nExpr = pList->nExpr; pInfo = sqlite3KeyInfoAlloc(db, nExpr-iStart, nExtra+1); if( pInfo ){ assert( sqlite3KeyInfoIsWriteable(pInfo) ); for(i=iStart, pItem=pList->a+iStart; ipExpr); if( !pColl ) pColl = db->pDfltColl; pInfo->aColl[i-iStart] = pColl; pInfo->aSortOrder[i-iStart] = pItem->sortOrder; } } return pInfo; } /* ** Name of the connection operator, used for error messages. */ static const char *selectOpName(int id){ char *z; switch( id ){ case TK_ALL: z = "UNION ALL"; break; case TK_INTERSECT: z = "INTERSECT"; break; case TK_EXCEPT: z = "EXCEPT"; break; default: z = "UNION"; break; } return z; } #ifndef SQLITE_OMIT_EXPLAIN /* ** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function ** is a no-op. Otherwise, it adds a single row of output to the EQP result, ** where the caption is of the form: ** ** "USE TEMP B-TREE FOR xxx" ** ** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which ** is determined by the zUsage argument. */ static void explainTempTable(Parse *pParse, const char *zUsage){ if( pParse->explain==2 ){ Vdbe *v = pParse->pVdbe; char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage); sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC); } } /* ** Assign expression b to lvalue a. A second, no-op, version of this macro ** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code ** in sqlite3Select() to assign values to structure member variables that ** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the ** code with #ifndef directives. */ # define explainSetInteger(a, b) a = b #else /* No-op versions of the explainXXX() functions and macros. */ # define explainTempTable(y,z) # define explainSetInteger(y,z) #endif #if !defined(SQLITE_OMIT_EXPLAIN) && !defined(SQLITE_OMIT_COMPOUND_SELECT) /* ** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function ** is a no-op. Otherwise, it adds a single row of output to the EQP result, ** where the caption is of one of the two forms: ** ** "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)" ** "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)" ** ** where iSub1 and iSub2 are the integers passed as the corresponding ** function parameters, and op is the text representation of the parameter ** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT, ** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is ** false, or the second form if it is true. */ static void explainComposite( Parse *pParse, /* Parse context */ int op, /* One of TK_UNION, TK_EXCEPT etc. */ int iSub1, /* Subquery id 1 */ int iSub2, /* Subquery id 2 */ int bUseTmp /* True if a temp table was used */ ){ assert( op==TK_UNION || op==TK_EXCEPT || op==TK_INTERSECT || op==TK_ALL ); if( pParse->explain==2 ){ Vdbe *v = pParse->pVdbe; char *zMsg = sqlite3MPrintf( pParse->db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2, bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op) ); sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC); } } #else /* No-op versions of the explainXXX() functions and macros. */ # define explainComposite(v,w,x,y,z) #endif /* ** If the inner loop was generated using a non-null pOrderBy argument, ** then the results were placed in a sorter. After the loop is terminated ** we need to run the sorter and output the results. The following ** routine generates the code needed to do that. */ static void generateSortTail( Parse *pParse, /* Parsing context */ Select *p, /* The SELECT statement */ SortCtx *pSort, /* Information on the ORDER BY clause */ int nColumn, /* Number of columns of data */ SelectDest *pDest /* Write the sorted results here */ ){ Vdbe *v = pParse->pVdbe; /* The prepared statement */ int addrBreak = pSort->labelDone; /* Jump here to exit loop */ int addrContinue = sqlite3VdbeMakeLabel(v); /* Jump here for next cycle */ int addr; int addrOnce = 0; int iTab; ExprList *pOrderBy = pSort->pOrderBy; int eDest = pDest->eDest; int iParm = pDest->iSDParm; int regRow; int regRowid; int nKey; int iSortTab; /* Sorter cursor to read from */ int nSortData; /* Trailing values to read from sorter */ int i; int bSeq; /* True if sorter record includes seq. no. */ #ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS struct ExprList_item *aOutEx = p->pEList->a; #endif assert( addrBreak<0 ); if( pSort->labelBkOut ){ sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut); sqlite3VdbeGoto(v, addrBreak); sqlite3VdbeResolveLabel(v, pSort->labelBkOut); } iTab = pSort->iECursor; if( eDest==SRT_Output || eDest==SRT_Coroutine || eDest==SRT_Mem ){ regRowid = 0; regRow = pDest->iSdst; nSortData = nColumn; }else{ regRowid = sqlite3GetTempReg(pParse); regRow = sqlite3GetTempRange(pParse, nColumn); nSortData = nColumn; } nKey = pOrderBy->nExpr - pSort->nOBSat; if( pSort->sortFlags & SORTFLAG_UseSorter ){ int regSortOut = ++pParse->nMem; iSortTab = pParse->nTab++; if( pSort->labelBkOut ){ addrOnce = sqlite3CodeOnce(pParse); VdbeCoverage(v); } sqlite3VdbeAddOp3(v, OP_OpenPseudo, iSortTab, regSortOut, nKey+1+nSortData); if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce); addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak); VdbeCoverage(v); codeOffset(v, p->iOffset, addrContinue); sqlite3VdbeAddOp3(v, OP_SorterData, iTab, regSortOut, iSortTab); bSeq = 0; }else{ addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); VdbeCoverage(v); codeOffset(v, p->iOffset, addrContinue); iSortTab = iTab; bSeq = 1; } for(i=0; izAffSdst) ); sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, nColumn, regRowid, pDest->zAffSdst, nColumn); sqlite3ExprCacheAffinityChange(pParse, regRow, nColumn); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid); break; } case SRT_Mem: { /* The LIMIT clause will terminate the loop for us */ break; } #endif default: { assert( eDest==SRT_Output || eDest==SRT_Coroutine ); testcase( eDest==SRT_Output ); testcase( eDest==SRT_Coroutine ); if( eDest==SRT_Output ){ sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iSdst, nColumn); sqlite3ExprCacheAffinityChange(pParse, pDest->iSdst, nColumn); }else{ sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm); } break; } } if( regRowid ){ if( eDest==SRT_Set ){ sqlite3ReleaseTempRange(pParse, regRow, nColumn); }else{ sqlite3ReleaseTempReg(pParse, regRow); } sqlite3ReleaseTempReg(pParse, regRowid); } /* The bottom of the loop */ sqlite3VdbeResolveLabel(v, addrContinue); if( pSort->sortFlags & SORTFLAG_UseSorter ){ sqlite3VdbeAddOp2(v, OP_SorterNext, iTab, addr); VdbeCoverage(v); }else{ sqlite3VdbeAddOp2(v, OP_Next, iTab, addr); VdbeCoverage(v); } if( pSort->regReturn ) sqlite3VdbeAddOp1(v, OP_Return, pSort->regReturn); sqlite3VdbeResolveLabel(v, addrBreak); } /* ** Return a pointer to a string containing the 'declaration type' of the ** expression pExpr. The string may be treated as static by the caller. ** ** Also try to estimate the size of the returned value and return that ** result in *pEstWidth. ** ** The declaration type is the exact datatype definition extracted from the ** original CREATE TABLE statement if the expression is a column. The ** declaration type for a ROWID field is INTEGER. Exactly when an expression ** is considered a column can be complex in the presence of subqueries. The ** result-set expression in all of the following SELECT statements is ** considered a column by this function. ** ** SELECT col FROM tbl; ** SELECT (SELECT col FROM tbl; ** SELECT (SELECT col FROM tbl); ** SELECT abc FROM (SELECT col AS abc FROM tbl); ** ** The declaration type for any expression other than a column is NULL. ** ** This routine has either 3 or 6 parameters depending on whether or not ** the SQLITE_ENABLE_COLUMN_METADATA compile-time option is used. */ #ifdef SQLITE_ENABLE_COLUMN_METADATA # define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,C,D,E,F) #else /* if !defined(SQLITE_ENABLE_COLUMN_METADATA) */ # define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,F) #endif static const char *columnTypeImpl( NameContext *pNC, Expr *pExpr, #ifdef SQLITE_ENABLE_COLUMN_METADATA const char **pzOrigDb, const char **pzOrigTab, const char **pzOrigCol, #endif u8 *pEstWidth ){ char const *zType = 0; int j; u8 estWidth = 1; #ifdef SQLITE_ENABLE_COLUMN_METADATA char const *zOrigDb = 0; char const *zOrigTab = 0; char const *zOrigCol = 0; #endif assert( pExpr!=0 ); assert( pNC->pSrcList!=0 ); switch( pExpr->op ){ case TK_AGG_COLUMN: case TK_COLUMN: { /* The expression is a column. Locate the table the column is being ** extracted from in NameContext.pSrcList. This table may be real ** database table or a subquery. */ Table *pTab = 0; /* Table structure column is extracted from */ Select *pS = 0; /* Select the column is extracted from */ int iCol = pExpr->iColumn; /* Index of column in pTab */ testcase( pExpr->op==TK_AGG_COLUMN ); testcase( pExpr->op==TK_COLUMN ); while( pNC && !pTab ){ SrcList *pTabList = pNC->pSrcList; for(j=0;jnSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++); if( jnSrc ){ pTab = pTabList->a[j].pTab; pS = pTabList->a[j].pSelect; }else{ pNC = pNC->pNext; } } if( pTab==0 ){ /* At one time, code such as "SELECT new.x" within a trigger would ** cause this condition to run. Since then, we have restructured how ** trigger code is generated and so this condition is no longer ** possible. However, it can still be true for statements like ** the following: ** ** CREATE TABLE t1(col INTEGER); ** SELECT (SELECT t1.col) FROM FROM t1; ** ** when columnType() is called on the expression "t1.col" in the ** sub-select. In this case, set the column type to NULL, even ** though it should really be "INTEGER". ** ** This is not a problem, as the column type of "t1.col" is never ** used. When columnType() is called on the expression ** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT ** branch below. */ break; } assert( pTab && pExpr->pTab==pTab ); if( pS ){ /* The "table" is actually a sub-select or a view in the FROM clause ** of the SELECT statement. Return the declaration type and origin ** data for the result-set column of the sub-select. */ if( iCol>=0 && ALWAYS(iColpEList->nExpr) ){ /* If iCol is less than zero, then the expression requests the ** rowid of the sub-select or view. This expression is legal (see ** test case misc2.2.2) - it always evaluates to NULL. ** ** The ALWAYS() is because iCol>=pS->pEList->nExpr will have been ** caught already by name resolution. */ NameContext sNC; Expr *p = pS->pEList->a[iCol].pExpr; sNC.pSrcList = pS->pSrc; sNC.pNext = pNC; sNC.pParse = pNC->pParse; zType = columnType(&sNC, p,&zOrigDb,&zOrigTab,&zOrigCol, &estWidth); } }else if( pTab->pSchema ){ /* A real table */ assert( !pS ); if( iCol<0 ) iCol = pTab->iPKey; assert( iCol==-1 || (iCol>=0 && iColnCol) ); #ifdef SQLITE_ENABLE_COLUMN_METADATA if( iCol<0 ){ zType = "INTEGER"; zOrigCol = "rowid"; }else{ zOrigCol = pTab->aCol[iCol].zName; zType = sqlite3ColumnType(&pTab->aCol[iCol],0); estWidth = pTab->aCol[iCol].szEst; } zOrigTab = pTab->zName; if( pNC->pParse ){ int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema); zOrigDb = pNC->pParse->db->aDb[iDb].zDbSName; } #else if( iCol<0 ){ zType = "INTEGER"; }else{ zType = sqlite3ColumnType(&pTab->aCol[iCol],0); estWidth = pTab->aCol[iCol].szEst; } #endif } break; } #ifndef SQLITE_OMIT_SUBQUERY case TK_SELECT: { /* The expression is a sub-select. Return the declaration type and ** origin info for the single column in the result set of the SELECT ** statement. */ NameContext sNC; Select *pS = pExpr->x.pSelect; Expr *p = pS->pEList->a[0].pExpr; assert( ExprHasProperty(pExpr, EP_xIsSelect) ); sNC.pSrcList = pS->pSrc; sNC.pNext = pNC; sNC.pParse = pNC->pParse; zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol, &estWidth); break; } #endif } #ifdef SQLITE_ENABLE_COLUMN_METADATA if( pzOrigDb ){ assert( pzOrigTab && pzOrigCol ); *pzOrigDb = zOrigDb; *pzOrigTab = zOrigTab; *pzOrigCol = zOrigCol; } #endif if( pEstWidth ) *pEstWidth = estWidth; return zType; } /* ** Generate code that will tell the VDBE the declaration types of columns ** in the result set. */ static void generateColumnTypes( Parse *pParse, /* Parser context */ SrcList *pTabList, /* List of tables */ ExprList *pEList /* Expressions defining the result set */ ){ #ifndef SQLITE_OMIT_DECLTYPE Vdbe *v = pParse->pVdbe; int i; NameContext sNC; sNC.pSrcList = pTabList; sNC.pParse = pParse; for(i=0; inExpr; i++){ Expr *p = pEList->a[i].pExpr; const char *zType; #ifdef SQLITE_ENABLE_COLUMN_METADATA const char *zOrigDb = 0; const char *zOrigTab = 0; const char *zOrigCol = 0; zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol, 0); /* The vdbe must make its own copy of the column-type and other ** column specific strings, in case the schema is reset before this ** virtual machine is deleted. */ sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT); sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT); sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT); #else zType = columnType(&sNC, p, 0, 0, 0, 0); #endif sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT); } #endif /* !defined(SQLITE_OMIT_DECLTYPE) */ } /* ** Generate code that will tell the VDBE the names of columns ** in the result set. This information is used to provide the ** azCol[] values in the callback. */ static void generateColumnNames( Parse *pParse, /* Parser context */ SrcList *pTabList, /* List of tables */ ExprList *pEList /* Expressions defining the result set */ ){ Vdbe *v = pParse->pVdbe; int i, j; sqlite3 *db = pParse->db; int fullNames, shortNames; #ifndef SQLITE_OMIT_EXPLAIN /* If this is an EXPLAIN, skip this step */ if( pParse->explain ){ return; } #endif if( pParse->colNamesSet || db->mallocFailed ) return; assert( v!=0 ); assert( pTabList!=0 ); pParse->colNamesSet = 1; fullNames = (db->flags & SQLITE_FullColNames)!=0; shortNames = (db->flags & SQLITE_ShortColNames)!=0; sqlite3VdbeSetNumCols(v, pEList->nExpr); for(i=0; inExpr; i++){ Expr *p; p = pEList->a[i].pExpr; if( NEVER(p==0) ) continue; if( pEList->a[i].zName ){ char *zName = pEList->a[i].zName; sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT); }else if( p->op==TK_COLUMN || p->op==TK_AGG_COLUMN ){ Table *pTab; char *zCol; int iCol = p->iColumn; for(j=0; ALWAYS(jnSrc); j++){ if( pTabList->a[j].iCursor==p->iTable ) break; } assert( jnSrc ); pTab = pTabList->a[j].pTab; if( iCol<0 ) iCol = pTab->iPKey; assert( iCol==-1 || (iCol>=0 && iColnCol) ); if( iCol<0 ){ zCol = "rowid"; }else{ zCol = pTab->aCol[iCol].zName; } if( !shortNames && !fullNames ){ sqlite3VdbeSetColName(v, i, COLNAME_NAME, sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC); }else if( fullNames ){ char *zName = 0; zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol); sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC); }else{ sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT); } }else{ const char *z = pEList->a[i].zSpan; z = z==0 ? sqlite3MPrintf(db, "column%d", i+1) : sqlite3DbStrDup(db, z); sqlite3VdbeSetColName(v, i, COLNAME_NAME, z, SQLITE_DYNAMIC); } } generateColumnTypes(pParse, pTabList, pEList); } /* ** Given an expression list (which is really the list of expressions ** that form the result set of a SELECT statement) compute appropriate ** column names for a table that would hold the expression list. ** ** All column names will be unique. ** ** Only the column names are computed. Column.zType, Column.zColl, ** and other fields of Column are zeroed. ** ** Return SQLITE_OK on success. If a memory allocation error occurs, ** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM. */ int sqlite3ColumnsFromExprList( Parse *pParse, /* Parsing context */ ExprList *pEList, /* Expr list from which to derive column names */ i16 *pnCol, /* Write the number of columns here */ Column **paCol /* Write the new column list here */ ){ sqlite3 *db = pParse->db; /* Database connection */ int i, j; /* Loop counters */ u32 cnt; /* Index added to make the name unique */ Column *aCol, *pCol; /* For looping over result columns */ int nCol; /* Number of columns in the result set */ Expr *p; /* Expression for a single result column */ char *zName; /* Column name */ int nName; /* Size of name in zName[] */ Hash ht; /* Hash table of column names */ sqlite3HashInit(&ht); if( pEList ){ nCol = pEList->nExpr; aCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol); testcase( aCol==0 ); }else{ nCol = 0; aCol = 0; } assert( nCol==(i16)nCol ); *pnCol = nCol; *paCol = aCol; for(i=0, pCol=aCol; imallocFailed; i++, pCol++){ /* Get an appropriate name for the column */ p = sqlite3ExprSkipCollate(pEList->a[i].pExpr); if( (zName = pEList->a[i].zName)!=0 ){ /* If the column contains an "AS " phrase, use as the name */ }else{ Expr *pColExpr = p; /* The expression that is the result column name */ Table *pTab; /* Table associated with this expression */ while( pColExpr->op==TK_DOT ){ pColExpr = pColExpr->pRight; assert( pColExpr!=0 ); } if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){ /* For columns use the column name name */ int iCol = pColExpr->iColumn; pTab = pColExpr->pTab; if( iCol<0 ) iCol = pTab->iPKey; zName = iCol>=0 ? pTab->aCol[iCol].zName : "rowid"; }else if( pColExpr->op==TK_ID ){ assert( !ExprHasProperty(pColExpr, EP_IntValue) ); zName = pColExpr->u.zToken; }else{ /* Use the original text of the column expression as its name */ zName = pEList->a[i].zSpan; } } zName = sqlite3MPrintf(db, "%s", zName); /* Make sure the column name is unique. If the name is not unique, ** append an integer to the name so that it becomes unique. */ cnt = 0; while( zName && sqlite3HashFind(&ht, zName)!=0 ){ nName = sqlite3Strlen30(zName); if( nName>0 ){ for(j=nName-1; j>0 && sqlite3Isdigit(zName[j]); j--){} if( zName[j]==':' ) nName = j; } zName = sqlite3MPrintf(db, "%.*z:%u", nName, zName, ++cnt); if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt); } pCol->zName = zName; sqlite3ColumnPropertiesFromName(0, pCol); if( zName && sqlite3HashInsert(&ht, zName, pCol)==pCol ){ sqlite3OomFault(db); } } sqlite3HashClear(&ht); if( db->mallocFailed ){ for(j=0; jdb; NameContext sNC; Column *pCol; CollSeq *pColl; int i; Expr *p; struct ExprList_item *a; u64 szAll = 0; assert( pSelect!=0 ); assert( (pSelect->selFlags & SF_Resolved)!=0 ); assert( pTab->nCol==pSelect->pEList->nExpr || db->mallocFailed ); if( db->mallocFailed ) return; memset(&sNC, 0, sizeof(sNC)); sNC.pSrcList = pSelect->pSrc; a = pSelect->pEList->a; for(i=0, pCol=pTab->aCol; inCol; i++, pCol++){ const char *zType; int n, m; p = a[i].pExpr; zType = columnType(&sNC, p, 0, 0, 0, &pCol->szEst); szAll += pCol->szEst; pCol->affinity = sqlite3ExprAffinity(p); if( zType && (m = sqlite3Strlen30(zType))>0 ){ n = sqlite3Strlen30(pCol->zName); pCol->zName = sqlite3DbReallocOrFree(db, pCol->zName, n+m+2); if( pCol->zName ){ memcpy(&pCol->zName[n+1], zType, m+1); pCol->colFlags |= COLFLAG_HASTYPE; } } if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_BLOB; pColl = sqlite3ExprCollSeq(pParse, p); if( pColl && pCol->zColl==0 ){ pCol->zColl = sqlite3DbStrDup(db, pColl->zName); } } pTab->szTabRow = sqlite3LogEst(szAll*4); } /* ** Given a SELECT statement, generate a Table structure that describes ** the result set of that SELECT. */ Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){ Table *pTab; sqlite3 *db = pParse->db; int savedFlags; savedFlags = db->flags; db->flags &= ~SQLITE_FullColNames; db->flags |= SQLITE_ShortColNames; sqlite3SelectPrep(pParse, pSelect, 0); if( pParse->nErr ) return 0; while( pSelect->pPrior ) pSelect = pSelect->pPrior; db->flags = savedFlags; pTab = sqlite3DbMallocZero(db, sizeof(Table) ); if( pTab==0 ){ return 0; } /* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside ** is disabled */ assert( db->lookaside.bDisable ); pTab->nRef = 1; pTab->zName = 0; pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) ); sqlite3ColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol); sqlite3SelectAddColumnTypeAndCollation(pParse, pTab, pSelect); pTab->iPKey = -1; if( db->mallocFailed ){ sqlite3DeleteTable(db, pTab); return 0; } return pTab; } /* ** Get a VDBE for the given parser context. Create a new one if necessary. ** If an error occurs, return NULL and leave a message in pParse. */ static SQLITE_NOINLINE Vdbe *allocVdbe(Parse *pParse){ Vdbe *v = pParse->pVdbe = sqlite3VdbeCreate(pParse); if( v ) sqlite3VdbeAddOp2(v, OP_Init, 0, 1); if( pParse->pToplevel==0 && OptimizationEnabled(pParse->db,SQLITE_FactorOutConst) ){ pParse->okConstFactor = 1; } return v; } Vdbe *sqlite3GetVdbe(Parse *pParse){ Vdbe *v = pParse->pVdbe; return v ? v : allocVdbe(pParse); } /* ** Compute the iLimit and iOffset fields of the SELECT based on the ** pLimit and pOffset expressions. pLimit and pOffset hold the expressions ** that appear in the original SQL statement after the LIMIT and OFFSET ** keywords. Or NULL if those keywords are omitted. iLimit and iOffset ** are the integer memory register numbers for counters used to compute ** the limit and offset. If there is no limit and/or offset, then ** iLimit and iOffset are negative. ** ** This routine changes the values of iLimit and iOffset only if ** a limit or offset is defined by pLimit and pOffset. iLimit and ** iOffset should have been preset to appropriate default values (zero) ** prior to calling this routine. ** ** The iOffset register (if it exists) is initialized to the value ** of the OFFSET. The iLimit register is initialized to LIMIT. Register ** iOffset+1 is initialized to LIMIT+OFFSET. ** ** Only if pLimit!=0 or pOffset!=0 do the limit registers get ** redefined. The UNION ALL operator uses this property to force ** the reuse of the same limit and offset registers across multiple ** SELECT statements. */ static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){ Vdbe *v = 0; int iLimit = 0; int iOffset; int n; if( p->iLimit ) return; /* ** "LIMIT -1" always shows all rows. There is some ** controversy about what the correct behavior should be. ** The current implementation interprets "LIMIT 0" to mean ** no rows. */ sqlite3ExprCacheClear(pParse); assert( p->pOffset==0 || p->pLimit!=0 ); if( p->pLimit ){ p->iLimit = iLimit = ++pParse->nMem; v = sqlite3GetVdbe(pParse); assert( v!=0 ); if( sqlite3ExprIsInteger(p->pLimit, &n) ){ sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit); VdbeComment((v, "LIMIT counter")); if( n==0 ){ sqlite3VdbeGoto(v, iBreak); }else if( n>=0 && p->nSelectRow>sqlite3LogEst((u64)n) ){ p->nSelectRow = sqlite3LogEst((u64)n); p->selFlags |= SF_FixedLimit; } }else{ sqlite3ExprCode(pParse, p->pLimit, iLimit); sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeCoverage(v); VdbeComment((v, "LIMIT counter")); sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, iBreak); VdbeCoverage(v); } if( p->pOffset ){ p->iOffset = iOffset = ++pParse->nMem; pParse->nMem++; /* Allocate an extra register for limit+offset */ sqlite3ExprCode(pParse, p->pOffset, iOffset); sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); VdbeCoverage(v); VdbeComment((v, "OFFSET counter")); sqlite3VdbeAddOp3(v, OP_OffsetLimit, iLimit, iOffset+1, iOffset); VdbeComment((v, "LIMIT+OFFSET")); } } } #ifndef SQLITE_OMIT_COMPOUND_SELECT /* ** Return the appropriate collating sequence for the iCol-th column of ** the result set for the compound-select statement "p". Return NULL if ** the column has no default collating sequence. ** ** The collating sequence for the compound select is taken from the ** left-most term of the select that has a collating sequence. */ static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){ CollSeq *pRet; if( p->pPrior ){ pRet = multiSelectCollSeq(pParse, p->pPrior, iCol); }else{ pRet = 0; } assert( iCol>=0 ); /* iCol must be less than p->pEList->nExpr. Otherwise an error would ** have been thrown during name resolution and we would not have gotten ** this far */ if( pRet==0 && ALWAYS(iColpEList->nExpr) ){ pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr); } return pRet; } /* ** The select statement passed as the second parameter is a compound SELECT ** with an ORDER BY clause. This function allocates and returns a KeyInfo ** structure suitable for implementing the ORDER BY. ** ** Space to hold the KeyInfo structure is obtained from malloc. The calling ** function is responsible for ensuring that this structure is eventually ** freed. */ static KeyInfo *multiSelectOrderByKeyInfo(Parse *pParse, Select *p, int nExtra){ ExprList *pOrderBy = p->pOrderBy; int nOrderBy = p->pOrderBy->nExpr; sqlite3 *db = pParse->db; KeyInfo *pRet = sqlite3KeyInfoAlloc(db, nOrderBy+nExtra, 1); if( pRet ){ int i; for(i=0; ia[i]; Expr *pTerm = pItem->pExpr; CollSeq *pColl; if( pTerm->flags & EP_Collate ){ pColl = sqlite3ExprCollSeq(pParse, pTerm); }else{ pColl = multiSelectCollSeq(pParse, p, pItem->u.x.iOrderByCol-1); if( pColl==0 ) pColl = db->pDfltColl; pOrderBy->a[i].pExpr = sqlite3ExprAddCollateString(pParse, pTerm, pColl->zName); } assert( sqlite3KeyInfoIsWriteable(pRet) ); pRet->aColl[i] = pColl; pRet->aSortOrder[i] = pOrderBy->a[i].sortOrder; } } return pRet; } #ifndef SQLITE_OMIT_CTE /* ** This routine generates VDBE code to compute the content of a WITH RECURSIVE ** query of the form: ** ** AS ( UNION [ALL] ) ** \___________/ \_______________/ ** p->pPrior p ** ** ** There is exactly one reference to the recursive-table in the FROM clause ** of recursive-query, marked with the SrcList->a[].fg.isRecursive flag. ** ** The setup-query runs once to generate an initial set of rows that go ** into a Queue table. Rows are extracted from the Queue table one by ** one. Each row extracted from Queue is output to pDest. Then the single ** extracted row (now in the iCurrent table) becomes the content of the ** recursive-table for a recursive-query run. The output of the recursive-query ** is added back into the Queue table. Then another row is extracted from Queue ** and the iteration continues until the Queue table is empty. ** ** If the compound query operator is UNION then no duplicate rows are ever ** inserted into the Queue table. The iDistinct table keeps a copy of all rows ** that have ever been inserted into Queue and causes duplicates to be ** discarded. If the operator is UNION ALL, then duplicates are allowed. ** ** If the query has an ORDER BY, then entries in the Queue table are kept in ** ORDER BY order and the first entry is extracted for each cycle. Without ** an ORDER BY, the Queue table is just a FIFO. ** ** If a LIMIT clause is provided, then the iteration stops after LIMIT rows ** have been output to pDest. A LIMIT of zero means to output no rows and a ** negative LIMIT means to output all rows. If there is also an OFFSET clause ** with a positive value, then the first OFFSET outputs are discarded rather ** than being sent to pDest. The LIMIT count does not begin until after OFFSET ** rows have been skipped. */ static void generateWithRecursiveQuery( Parse *pParse, /* Parsing context */ Select *p, /* The recursive SELECT to be coded */ SelectDest *pDest /* What to do with query results */ ){ SrcList *pSrc = p->pSrc; /* The FROM clause of the recursive query */ int nCol = p->pEList->nExpr; /* Number of columns in the recursive table */ Vdbe *v = pParse->pVdbe; /* The prepared statement under construction */ Select *pSetup = p->pPrior; /* The setup query */ int addrTop; /* Top of the loop */ int addrCont, addrBreak; /* CONTINUE and BREAK addresses */ int iCurrent = 0; /* The Current table */ int regCurrent; /* Register holding Current table */ int iQueue; /* The Queue table */ int iDistinct = 0; /* To ensure unique results if UNION */ int eDest = SRT_Fifo; /* How to write to Queue */ SelectDest destQueue; /* SelectDest targetting the Queue table */ int i; /* Loop counter */ int rc; /* Result code */ ExprList *pOrderBy; /* The ORDER BY clause */ Expr *pLimit, *pOffset; /* Saved LIMIT and OFFSET */ int regLimit, regOffset; /* Registers used by LIMIT and OFFSET */ /* Obtain authorization to do a recursive query */ if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return; /* Process the LIMIT and OFFSET clauses, if they exist */ addrBreak = sqlite3VdbeMakeLabel(v); computeLimitRegisters(pParse, p, addrBreak); pLimit = p->pLimit; pOffset = p->pOffset; regLimit = p->iLimit; regOffset = p->iOffset; p->pLimit = p->pOffset = 0; p->iLimit = p->iOffset = 0; pOrderBy = p->pOrderBy; /* Locate the cursor number of the Current table */ for(i=0; ALWAYS(inSrc); i++){ if( pSrc->a[i].fg.isRecursive ){ iCurrent = pSrc->a[i].iCursor; break; } } /* Allocate cursors numbers for Queue and Distinct. The cursor number for ** the Distinct table must be exactly one greater than Queue in order ** for the SRT_DistFifo and SRT_DistQueue destinations to work. */ iQueue = pParse->nTab++; if( p->op==TK_UNION ){ eDest = pOrderBy ? SRT_DistQueue : SRT_DistFifo; iDistinct = pParse->nTab++; }else{ eDest = pOrderBy ? SRT_Queue : SRT_Fifo; } sqlite3SelectDestInit(&destQueue, eDest, iQueue); /* Allocate cursors for Current, Queue, and Distinct. */ regCurrent = ++pParse->nMem; sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol); if( pOrderBy ){ KeyInfo *pKeyInfo = multiSelectOrderByKeyInfo(pParse, p, 1); sqlite3VdbeAddOp4(v, OP_OpenEphemeral, iQueue, pOrderBy->nExpr+2, 0, (char*)pKeyInfo, P4_KEYINFO); destQueue.pOrderBy = pOrderBy; }else{ sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iQueue, nCol); } VdbeComment((v, "Queue table")); if( iDistinct ){ p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iDistinct, 0); p->selFlags |= SF_UsesEphemeral; } /* Detach the ORDER BY clause from the compound SELECT */ p->pOrderBy = 0; /* Store the results of the setup-query in Queue. */ pSetup->pNext = 0; rc = sqlite3Select(pParse, pSetup, &destQueue); pSetup->pNext = p; if( rc ) goto end_of_recursive_query; /* Find the next row in the Queue and output that row */ addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, iQueue, addrBreak); VdbeCoverage(v); /* Transfer the next row in Queue over to Current */ sqlite3VdbeAddOp1(v, OP_NullRow, iCurrent); /* To reset column cache */ if( pOrderBy ){ sqlite3VdbeAddOp3(v, OP_Column, iQueue, pOrderBy->nExpr+1, regCurrent); }else{ sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent); } sqlite3VdbeAddOp1(v, OP_Delete, iQueue); /* Output the single row in Current */ addrCont = sqlite3VdbeMakeLabel(v); codeOffset(v, regOffset, addrCont); selectInnerLoop(pParse, p, p->pEList, iCurrent, 0, 0, pDest, addrCont, addrBreak); if( regLimit ){ sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak); VdbeCoverage(v); } sqlite3VdbeResolveLabel(v, addrCont); /* Execute the recursive SELECT taking the single row in Current as ** the value for the recursive-table. Store the results in the Queue. */ if( p->selFlags & SF_Aggregate ){ sqlite3ErrorMsg(pParse, "recursive aggregate queries not supported"); }else{ p->pPrior = 0; sqlite3Select(pParse, p, &destQueue); assert( p->pPrior==0 ); p->pPrior = pSetup; } /* Keep running the loop until the Queue is empty */ sqlite3VdbeGoto(v, addrTop); sqlite3VdbeResolveLabel(v, addrBreak); end_of_recursive_query: sqlite3ExprListDelete(pParse->db, p->pOrderBy); p->pOrderBy = pOrderBy; p->pLimit = pLimit; p->pOffset = pOffset; return; } #endif /* SQLITE_OMIT_CTE */ /* Forward references */ static int multiSelectOrderBy( Parse *pParse, /* Parsing context */ Select *p, /* The right-most of SELECTs to be coded */ SelectDest *pDest /* What to do with query results */ ); /* ** Handle the special case of a compound-select that originates from a ** VALUES clause. By handling this as a special case, we avoid deep ** recursion, and thus do not need to enforce the SQLITE_LIMIT_COMPOUND_SELECT ** on a VALUES clause. ** ** Because the Select object originates from a VALUES clause: ** (1) It has no LIMIT or OFFSET ** (2) All terms are UNION ALL ** (3) There is no ORDER BY clause */ static int multiSelectValues( Parse *pParse, /* Parsing context */ Select *p, /* The right-most of SELECTs to be coded */ SelectDest *pDest /* What to do with query results */ ){ Select *pPrior; int nRow = 1; int rc = 0; assert( p->selFlags & SF_MultiValue ); do{ assert( p->selFlags & SF_Values ); assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) ); assert( p->pLimit==0 ); assert( p->pOffset==0 ); assert( p->pNext==0 || p->pEList->nExpr==p->pNext->pEList->nExpr ); if( p->pPrior==0 ) break; assert( p->pPrior->pNext==p ); p = p->pPrior; nRow++; }while(1); while( p ){ pPrior = p->pPrior; p->pPrior = 0; rc = sqlite3Select(pParse, p, pDest); p->pPrior = pPrior; if( rc ) break; p->nSelectRow = nRow; p = p->pNext; } return rc; } /* ** This routine is called to process a compound query form from ** two or more separate queries using UNION, UNION ALL, EXCEPT, or ** INTERSECT ** ** "p" points to the right-most of the two queries. the query on the ** left is p->pPrior. The left query could also be a compound query ** in which case this routine will be called recursively. ** ** The results of the total query are to be written into a destination ** of type eDest with parameter iParm. ** ** Example 1: Consider a three-way compound SQL statement. ** ** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3 ** ** This statement is parsed up as follows: ** ** SELECT c FROM t3 ** | ** `-----> SELECT b FROM t2 ** | ** `------> SELECT a FROM t1 ** ** The arrows in the diagram above represent the Select.pPrior pointer. ** So if this routine is called with p equal to the t3 query, then ** pPrior will be the t2 query. p->op will be TK_UNION in this case. ** ** Notice that because of the way SQLite parses compound SELECTs, the ** individual selects always group from left to right. */ static int multiSelect( Parse *pParse, /* Parsing context */ Select *p, /* The right-most of SELECTs to be coded */ SelectDest *pDest /* What to do with query results */ ){ int rc = SQLITE_OK; /* Success code from a subroutine */ Select *pPrior; /* Another SELECT immediately to our left */ Vdbe *v; /* Generate code to this VDBE */ SelectDest dest; /* Alternative data destination */ Select *pDelete = 0; /* Chain of simple selects to delete */ sqlite3 *db; /* Database connection */ #ifndef SQLITE_OMIT_EXPLAIN int iSub1 = 0; /* EQP id of left-hand query */ int iSub2 = 0; /* EQP id of right-hand query */ #endif /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT. */ assert( p && p->pPrior ); /* Calling function guarantees this much */ assert( (p->selFlags & SF_Recursive)==0 || p->op==TK_ALL || p->op==TK_UNION ); db = pParse->db; pPrior = p->pPrior; dest = *pDest; if( pPrior->pOrderBy ){ sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before", selectOpName(p->op)); rc = 1; goto multi_select_end; } if( pPrior->pLimit ){ sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before", selectOpName(p->op)); rc = 1; goto multi_select_end; } v = sqlite3GetVdbe(pParse); assert( v!=0 ); /* The VDBE already created by calling function */ /* Create the destination temporary table if necessary */ if( dest.eDest==SRT_EphemTab ){ assert( p->pEList ); sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iSDParm, p->pEList->nExpr); dest.eDest = SRT_Table; } /* Special handling for a compound-select that originates as a VALUES clause. */ if( p->selFlags & SF_MultiValue ){ rc = multiSelectValues(pParse, p, &dest); goto multi_select_end; } /* Make sure all SELECTs in the statement have the same number of elements ** in their result sets. */ assert( p->pEList && pPrior->pEList ); assert( p->pEList->nExpr==pPrior->pEList->nExpr ); #ifndef SQLITE_OMIT_CTE if( p->selFlags & SF_Recursive ){ generateWithRecursiveQuery(pParse, p, &dest); }else #endif /* Compound SELECTs that have an ORDER BY clause are handled separately. */ if( p->pOrderBy ){ return multiSelectOrderBy(pParse, p, pDest); }else /* Generate code for the left and right SELECT statements. */ switch( p->op ){ case TK_ALL: { int addr = 0; int nLimit; assert( !pPrior->pLimit ); pPrior->iLimit = p->iLimit; pPrior->iOffset = p->iOffset; pPrior->pLimit = p->pLimit; pPrior->pOffset = p->pOffset; explainSetInteger(iSub1, pParse->iNextSelectId); rc = sqlite3Select(pParse, pPrior, &dest); p->pLimit = 0; p->pOffset = 0; if( rc ){ goto multi_select_end; } p->pPrior = 0; p->iLimit = pPrior->iLimit; p->iOffset = pPrior->iOffset; if( p->iLimit ){ addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v); VdbeComment((v, "Jump ahead if LIMIT reached")); if( p->iOffset ){ sqlite3VdbeAddOp3(v, OP_OffsetLimit, p->iLimit, p->iOffset+1, p->iOffset); } } explainSetInteger(iSub2, pParse->iNextSelectId); rc = sqlite3Select(pParse, p, &dest); testcase( rc!=SQLITE_OK ); pDelete = p->pPrior; p->pPrior = pPrior; p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow); if( pPrior->pLimit && sqlite3ExprIsInteger(pPrior->pLimit, &nLimit) && nLimit>0 && p->nSelectRow > sqlite3LogEst((u64)nLimit) ){ p->nSelectRow = sqlite3LogEst((u64)nLimit); } if( addr ){ sqlite3VdbeJumpHere(v, addr); } break; } case TK_EXCEPT: case TK_UNION: { int unionTab; /* Cursor number of the temporary table holding result */ u8 op = 0; /* One of the SRT_ operations to apply to self */ int priorOp; /* The SRT_ operation to apply to prior selects */ Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */ int addr; SelectDest uniondest; testcase( p->op==TK_EXCEPT ); testcase( p->op==TK_UNION ); priorOp = SRT_Union; if( dest.eDest==priorOp ){ /* We can reuse a temporary table generated by a SELECT to our ** right. */ assert( p->pLimit==0 ); /* Not allowed on leftward elements */ assert( p->pOffset==0 ); /* Not allowed on leftward elements */ unionTab = dest.iSDParm; }else{ /* We will need to create our own temporary table to hold the ** intermediate results. */ unionTab = pParse->nTab++; assert( p->pOrderBy==0 ); addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0); assert( p->addrOpenEphm[0] == -1 ); p->addrOpenEphm[0] = addr; findRightmost(p)->selFlags |= SF_UsesEphemeral; assert( p->pEList ); } /* Code the SELECT statements to our left */ assert( !pPrior->pOrderBy ); sqlite3SelectDestInit(&uniondest, priorOp, unionTab); explainSetInteger(iSub1, pParse->iNextSelectId); rc = sqlite3Select(pParse, pPrior, &uniondest); if( rc ){ goto multi_select_end; } /* Code the current SELECT statement */ if( p->op==TK_EXCEPT ){ op = SRT_Except; }else{ assert( p->op==TK_UNION ); op = SRT_Union; } p->pPrior = 0; pLimit = p->pLimit; p->pLimit = 0; pOffset = p->pOffset; p->pOffset = 0; uniondest.eDest = op; explainSetInteger(iSub2, pParse->iNextSelectId); rc = sqlite3Select(pParse, p, &uniondest); testcase( rc!=SQLITE_OK ); /* Query flattening in sqlite3Select() might refill p->pOrderBy. ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */ sqlite3ExprListDelete(db, p->pOrderBy); pDelete = p->pPrior; p->pPrior = pPrior; p->pOrderBy = 0; if( p->op==TK_UNION ){ p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow); } sqlite3ExprDelete(db, p->pLimit); p->pLimit = pLimit; p->pOffset = pOffset; p->iLimit = 0; p->iOffset = 0; /* Convert the data in the temporary table into whatever form ** it is that we currently need. */ assert( unionTab==dest.iSDParm || dest.eDest!=priorOp ); if( dest.eDest!=priorOp ){ int iCont, iBreak, iStart; assert( p->pEList ); if( dest.eDest==SRT_Output ){ Select *pFirst = p; while( pFirst->pPrior ) pFirst = pFirst->pPrior; generateColumnNames(pParse, pFirst->pSrc, pFirst->pEList); } iBreak = sqlite3VdbeMakeLabel(v); iCont = sqlite3VdbeMakeLabel(v); computeLimitRegisters(pParse, p, iBreak); sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); VdbeCoverage(v); iStart = sqlite3VdbeCurrentAddr(v); selectInnerLoop(pParse, p, p->pEList, unionTab, 0, 0, &dest, iCont, iBreak); sqlite3VdbeResolveLabel(v, iCont); sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v); sqlite3VdbeResolveLabel(v, iBreak); sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0); } break; } default: assert( p->op==TK_INTERSECT ); { int tab1, tab2; int iCont, iBreak, iStart; Expr *pLimit, *pOffset; int addr; SelectDest intersectdest; int r1; /* INTERSECT is different from the others since it requires ** two temporary tables. Hence it has its own case. Begin ** by allocating the tables we will need. */ tab1 = pParse->nTab++; tab2 = pParse->nTab++; assert( p->pOrderBy==0 ); addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0); assert( p->addrOpenEphm[0] == -1 ); p->addrOpenEphm[0] = addr; findRightmost(p)->selFlags |= SF_UsesEphemeral; assert( p->pEList ); /* Code the SELECTs to our left into temporary table "tab1". */ sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1); explainSetInteger(iSub1, pParse->iNextSelectId); rc = sqlite3Select(pParse, pPrior, &intersectdest); if( rc ){ goto multi_select_end; } /* Code the current SELECT into temporary table "tab2" */ addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0); assert( p->addrOpenEphm[1] == -1 ); p->addrOpenEphm[1] = addr; p->pPrior = 0; pLimit = p->pLimit; p->pLimit = 0; pOffset = p->pOffset; p->pOffset = 0; intersectdest.iSDParm = tab2; explainSetInteger(iSub2, pParse->iNextSelectId); rc = sqlite3Select(pParse, p, &intersectdest); testcase( rc!=SQLITE_OK ); pDelete = p->pPrior; p->pPrior = pPrior; if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow; sqlite3ExprDelete(db, p->pLimit); p->pLimit = pLimit; p->pOffset = pOffset; /* Generate code to take the intersection of the two temporary ** tables. */ assert( p->pEList ); if( dest.eDest==SRT_Output ){ Select *pFirst = p; while( pFirst->pPrior ) pFirst = pFirst->pPrior; generateColumnNames(pParse, pFirst->pSrc, pFirst->pEList); } iBreak = sqlite3VdbeMakeLabel(v); iCont = sqlite3VdbeMakeLabel(v); computeLimitRegisters(pParse, p, iBreak); sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); VdbeCoverage(v); r1 = sqlite3GetTempReg(pParse); iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1); sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0); VdbeCoverage(v); sqlite3ReleaseTempReg(pParse, r1); selectInnerLoop(pParse, p, p->pEList, tab1, 0, 0, &dest, iCont, iBreak); sqlite3VdbeResolveLabel(v, iCont); sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v); sqlite3VdbeResolveLabel(v, iBreak); sqlite3VdbeAddOp2(v, OP_Close, tab2, 0); sqlite3VdbeAddOp2(v, OP_Close, tab1, 0); break; } } explainComposite(pParse, p->op, iSub1, iSub2, p->op!=TK_ALL); /* Compute collating sequences used by ** temporary tables needed to implement the compound select. ** Attach the KeyInfo structure to all temporary tables. ** ** This section is run by the right-most SELECT statement only. ** SELECT statements to the left always skip this part. The right-most ** SELECT might also skip this part if it has no ORDER BY clause and ** no temp tables are required. */ if( p->selFlags & SF_UsesEphemeral ){ int i; /* Loop counter */ KeyInfo *pKeyInfo; /* Collating sequence for the result set */ Select *pLoop; /* For looping through SELECT statements */ CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */ int nCol; /* Number of columns in result set */ assert( p->pNext==0 ); nCol = p->pEList->nExpr; pKeyInfo = sqlite3KeyInfoAlloc(db, nCol, 1); if( !pKeyInfo ){ rc = SQLITE_NOMEM_BKPT; goto multi_select_end; } for(i=0, apColl=pKeyInfo->aColl; ipDfltColl; } } for(pLoop=p; pLoop; pLoop=pLoop->pPrior){ for(i=0; i<2; i++){ int addr = pLoop->addrOpenEphm[i]; if( addr<0 ){ /* If [0] is unused then [1] is also unused. So we can ** always safely abort as soon as the first unused slot is found */ assert( pLoop->addrOpenEphm[1]<0 ); break; } sqlite3VdbeChangeP2(v, addr, nCol); sqlite3VdbeChangeP4(v, addr, (char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO); pLoop->addrOpenEphm[i] = -1; } } sqlite3KeyInfoUnref(pKeyInfo); } multi_select_end: pDest->iSdst = dest.iSdst; pDest->nSdst = dest.nSdst; sqlite3SelectDelete(db, pDelete); return rc; } #endif /* SQLITE_OMIT_COMPOUND_SELECT */ /* ** Error message for when two or more terms of a compound select have different ** size result sets. */ void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){ if( p->selFlags & SF_Values ){ sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms"); }else{ sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s" " do not have the same number of result columns", selectOpName(p->op)); } } /* ** Code an output subroutine for a coroutine implementation of a ** SELECT statment. ** ** The data to be output is contained in pIn->iSdst. There are ** pIn->nSdst columns to be output. pDest is where the output should ** be sent. ** ** regReturn is the number of the register holding the subroutine ** return address. ** ** If regPrev>0 then it is the first register in a vector that ** records the previous output. mem[regPrev] is a flag that is false ** if there has been no previous output. If regPrev>0 then code is ** generated to suppress duplicates. pKeyInfo is used for comparing ** keys. ** ** If the LIMIT found in p->iLimit is reached, jump immediately to ** iBreak. */ static int generateOutputSubroutine( Parse *pParse, /* Parsing context */ Select *p, /* The SELECT statement */ SelectDest *pIn, /* Coroutine supplying data */ SelectDest *pDest, /* Where to send the data */ int regReturn, /* The return address register */ int regPrev, /* Previous result register. No uniqueness if 0 */ KeyInfo *pKeyInfo, /* For comparing with previous entry */ int iBreak /* Jump here if we hit the LIMIT */ ){ Vdbe *v = pParse->pVdbe; int iContinue; int addr; addr = sqlite3VdbeCurrentAddr(v); iContinue = sqlite3VdbeMakeLabel(v); /* Suppress duplicates for UNION, EXCEPT, and INTERSECT */ if( regPrev ){ int addr1, addr2; addr1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev); VdbeCoverage(v); addr2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iSdst, regPrev+1, pIn->nSdst, (char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO); sqlite3VdbeAddOp3(v, OP_Jump, addr2+2, iContinue, addr2+2); VdbeCoverage(v); sqlite3VdbeJumpHere(v, addr1); sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1); sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev); } if( pParse->db->mallocFailed ) return 0; /* Suppress the first OFFSET entries if there is an OFFSET clause */ codeOffset(v, p->iOffset, iContinue); assert( pDest->eDest!=SRT_Exists ); assert( pDest->eDest!=SRT_Table ); switch( pDest->eDest ){ /* Store the result as data using a unique key. */ case SRT_EphemTab: { int r1 = sqlite3GetTempReg(pParse); int r2 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst, r1); sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iSDParm, r2); sqlite3VdbeAddOp3(v, OP_Insert, pDest->iSDParm, r1, r2); sqlite3VdbeChangeP5(v, OPFLAG_APPEND); sqlite3ReleaseTempReg(pParse, r2); sqlite3ReleaseTempReg(pParse, r1); break; } #ifndef SQLITE_OMIT_SUBQUERY /* If we are creating a set for an "expr IN (SELECT ...)" construct, ** then there should be a single item on the stack. Write this ** item into the set table with bogus data. */ case SRT_Set: { int r1; assert( pIn->nSdst==1 || pParse->nErr>0 ); r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst, r1, pDest->zAffSdst,1); sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, 1); sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iSDParm, r1); sqlite3ReleaseTempReg(pParse, r1); break; } /* If this is a scalar select that is part of an expression, then ** store the results in the appropriate memory cell and break out ** of the scan loop. */ case SRT_Mem: { assert( pIn->nSdst==1 || pParse->nErr>0 ); testcase( pIn->nSdst!=1 ); sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSDParm, 1); /* The LIMIT clause will jump out of the loop for us */ break; } #endif /* #ifndef SQLITE_OMIT_SUBQUERY */ /* The results are stored in a sequence of registers ** starting at pDest->iSdst. Then the co-routine yields. */ case SRT_Coroutine: { if( pDest->iSdst==0 ){ pDest->iSdst = sqlite3GetTempRange(pParse, pIn->nSdst); pDest->nSdst = pIn->nSdst; } sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSdst, pIn->nSdst); sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm); break; } /* If none of the above, then the result destination must be ** SRT_Output. This routine is never called with any other ** destination other than the ones handled above or SRT_Output. ** ** For SRT_Output, results are stored in a sequence of registers. ** Then the OP_ResultRow opcode is used to cause sqlite3_step() to ** return the next row of result. */ default: { assert( pDest->eDest==SRT_Output ); sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iSdst, pIn->nSdst); sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, pIn->nSdst); break; } } /* Jump to the end of the loop if the LIMIT is reached. */ if( p->iLimit ){ sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v); } /* Generate the subroutine return */ sqlite3VdbeResolveLabel(v, iContinue); sqlite3VdbeAddOp1(v, OP_Return, regReturn); return addr; } /* ** Alternative compound select code generator for cases when there ** is an ORDER BY clause. ** ** We assume a query of the following form: ** ** ORDER BY ** ** is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea ** is to code both and with the ORDER BY clause as ** co-routines. Then run the co-routines in parallel and merge the results ** into the output. In addition to the two coroutines (called selectA and ** selectB) there are 7 subroutines: ** ** outA: Move the output of the selectA coroutine into the output ** of the compound query. ** ** outB: Move the output of the selectB coroutine into the output ** of the compound query. (Only generated for UNION and ** UNION ALL. EXCEPT and INSERTSECT never output a row that ** appears only in B.) ** ** AltB: Called when there is data from both coroutines and AB. ** ** EofA: Called when data is exhausted from selectA. ** ** EofB: Called when data is exhausted from selectB. ** ** The implementation of the latter five subroutines depend on which ** is used: ** ** ** UNION ALL UNION EXCEPT INTERSECT ** ------------- ----------------- -------------- ----------------- ** AltB: outA, nextA outA, nextA outA, nextA nextA ** ** AeqB: outA, nextA nextA nextA outA, nextA ** ** AgtB: outB, nextB outB, nextB nextB nextB ** ** EofA: outB, nextB outB, nextB halt halt ** ** EofB: outA, nextA outA, nextA outA, nextA halt ** ** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA ** causes an immediate jump to EofA and an EOF on B following nextB causes ** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or ** following nextX causes a jump to the end of the select processing. ** ** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled ** within the output subroutine. The regPrev register set holds the previously ** output value. A comparison is made against this value and the output ** is skipped if the next results would be the same as the previous. ** ** The implementation plan is to implement the two coroutines and seven ** subroutines first, then put the control logic at the bottom. Like this: ** ** goto Init ** coA: coroutine for left query (A) ** coB: coroutine for right query (B) ** outA: output one row of A ** outB: output one row of B (UNION and UNION ALL only) ** EofA: ... ** EofB: ... ** AltB: ... ** AeqB: ... ** AgtB: ... ** Init: initialize coroutine registers ** yield coA ** if eof(A) goto EofA ** yield coB ** if eof(B) goto EofB ** Cmpr: Compare A, B ** Jump AltB, AeqB, AgtB ** End: ... ** ** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not ** actually called using Gosub and they do not Return. EofA and EofB loop ** until all data is exhausted then jump to the "end" labe. AltB, AeqB, ** and AgtB jump to either L2 or to one of EofA or EofB. */ #ifndef SQLITE_OMIT_COMPOUND_SELECT static int multiSelectOrderBy( Parse *pParse, /* Parsing context */ Select *p, /* The right-most of SELECTs to be coded */ SelectDest *pDest /* What to do with query results */ ){ int i, j; /* Loop counters */ Select *pPrior; /* Another SELECT immediately to our left */ Vdbe *v; /* Generate code to this VDBE */ SelectDest destA; /* Destination for coroutine A */ SelectDest destB; /* Destination for coroutine B */ int regAddrA; /* Address register for select-A coroutine */ int regAddrB; /* Address register for select-B coroutine */ int addrSelectA; /* Address of the select-A coroutine */ int addrSelectB; /* Address of the select-B coroutine */ int regOutA; /* Address register for the output-A subroutine */ int regOutB; /* Address register for the output-B subroutine */ int addrOutA; /* Address of the output-A subroutine */ int addrOutB = 0; /* Address of the output-B subroutine */ int addrEofA; /* Address of the select-A-exhausted subroutine */ int addrEofA_noB; /* Alternate addrEofA if B is uninitialized */ int addrEofB; /* Address of the select-B-exhausted subroutine */ int addrAltB; /* Address of the AB subroutine */ int regLimitA; /* Limit register for select-A */ int regLimitB; /* Limit register for select-A */ int regPrev; /* A range of registers to hold previous output */ int savedLimit; /* Saved value of p->iLimit */ int savedOffset; /* Saved value of p->iOffset */ int labelCmpr; /* Label for the start of the merge algorithm */ int labelEnd; /* Label for the end of the overall SELECT stmt */ int addr1; /* Jump instructions that get retargetted */ int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */ KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */ KeyInfo *pKeyMerge; /* Comparison information for merging rows */ sqlite3 *db; /* Database connection */ ExprList *pOrderBy; /* The ORDER BY clause */ int nOrderBy; /* Number of terms in the ORDER BY clause */ int *aPermute; /* Mapping from ORDER BY terms to result set columns */ #ifndef SQLITE_OMIT_EXPLAIN int iSub1; /* EQP id of left-hand query */ int iSub2; /* EQP id of right-hand query */ #endif assert( p->pOrderBy!=0 ); assert( pKeyDup==0 ); /* "Managed" code needs this. Ticket #3382. */ db = pParse->db; v = pParse->pVdbe; assert( v!=0 ); /* Already thrown the error if VDBE alloc failed */ labelEnd = sqlite3VdbeMakeLabel(v); labelCmpr = sqlite3VdbeMakeLabel(v); /* Patch up the ORDER BY clause */ op = p->op; pPrior = p->pPrior; assert( pPrior->pOrderBy==0 ); pOrderBy = p->pOrderBy; assert( pOrderBy ); nOrderBy = pOrderBy->nExpr; /* For operators other than UNION ALL we have to make sure that ** the ORDER BY clause covers every term of the result set. Add ** terms to the ORDER BY clause as necessary. */ if( op!=TK_ALL ){ for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){ struct ExprList_item *pItem; for(j=0, pItem=pOrderBy->a; ju.x.iOrderByCol>0 ); if( pItem->u.x.iOrderByCol==i ) break; } if( j==nOrderBy ){ Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0); if( pNew==0 ) return SQLITE_NOMEM_BKPT; pNew->flags |= EP_IntValue; pNew->u.iValue = i; pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew); if( pOrderBy ) pOrderBy->a[nOrderBy++].u.x.iOrderByCol = (u16)i; } } } /* Compute the comparison permutation and keyinfo that is used with ** the permutation used to determine if the next ** row of results comes from selectA or selectB. Also add explicit ** collations to the ORDER BY clause terms so that when the subqueries ** to the right and the left are evaluated, they use the correct ** collation. */ aPermute = sqlite3DbMallocRawNN(db, sizeof(int)*(nOrderBy + 1)); if( aPermute ){ struct ExprList_item *pItem; aPermute[0] = nOrderBy; for(i=1, pItem=pOrderBy->a; i<=nOrderBy; i++, pItem++){ assert( pItem->u.x.iOrderByCol>0 ); assert( pItem->u.x.iOrderByCol<=p->pEList->nExpr ); aPermute[i] = pItem->u.x.iOrderByCol - 1; } pKeyMerge = multiSelectOrderByKeyInfo(pParse, p, 1); }else{ pKeyMerge = 0; } /* Reattach the ORDER BY clause to the query. */ p->pOrderBy = pOrderBy; pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0); /* Allocate a range of temporary registers and the KeyInfo needed ** for the logic that removes duplicate result rows when the ** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL). */ if( op==TK_ALL ){ regPrev = 0; }else{ int nExpr = p->pEList->nExpr; assert( nOrderBy>=nExpr || db->mallocFailed ); regPrev = pParse->nMem+1; pParse->nMem += nExpr+1; sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev); pKeyDup = sqlite3KeyInfoAlloc(db, nExpr, 1); if( pKeyDup ){ assert( sqlite3KeyInfoIsWriteable(pKeyDup) ); for(i=0; iaColl[i] = multiSelectCollSeq(pParse, p, i); pKeyDup->aSortOrder[i] = 0; } } } /* Separate the left and the right query from one another */ p->pPrior = 0; pPrior->pNext = 0; sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER"); if( pPrior->pPrior==0 ){ sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER"); } /* Compute the limit registers */ computeLimitRegisters(pParse, p, labelEnd); if( p->iLimit && op==TK_ALL ){ regLimitA = ++pParse->nMem; regLimitB = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit, regLimitA); sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB); }else{ regLimitA = regLimitB = 0; } sqlite3ExprDelete(db, p->pLimit); p->pLimit = 0; sqlite3ExprDelete(db, p->pOffset); p->pOffset = 0; regAddrA = ++pParse->nMem; regAddrB = ++pParse->nMem; regOutA = ++pParse->nMem; regOutB = ++pParse->nMem; sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA); sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB); /* Generate a coroutine to evaluate the SELECT statement to the ** left of the compound operator - the "A" select. */ addrSelectA = sqlite3VdbeCurrentAddr(v) + 1; addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA); VdbeComment((v, "left SELECT")); pPrior->iLimit = regLimitA; explainSetInteger(iSub1, pParse->iNextSelectId); sqlite3Select(pParse, pPrior, &destA); sqlite3VdbeEndCoroutine(v, regAddrA); sqlite3VdbeJumpHere(v, addr1); /* Generate a coroutine to evaluate the SELECT statement on ** the right - the "B" select */ addrSelectB = sqlite3VdbeCurrentAddr(v) + 1; addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB); VdbeComment((v, "right SELECT")); savedLimit = p->iLimit; savedOffset = p->iOffset; p->iLimit = regLimitB; p->iOffset = 0; explainSetInteger(iSub2, pParse->iNextSelectId); sqlite3Select(pParse, p, &destB); p->iLimit = savedLimit; p->iOffset = savedOffset; sqlite3VdbeEndCoroutine(v, regAddrB); /* Generate a subroutine that outputs the current row of the A ** select as the next output row of the compound select. */ VdbeNoopComment((v, "Output routine for A")); addrOutA = generateOutputSubroutine(pParse, p, &destA, pDest, regOutA, regPrev, pKeyDup, labelEnd); /* Generate a subroutine that outputs the current row of the B ** select as the next output row of the compound select. */ if( op==TK_ALL || op==TK_UNION ){ VdbeNoopComment((v, "Output routine for B")); addrOutB = generateOutputSubroutine(pParse, p, &destB, pDest, regOutB, regPrev, pKeyDup, labelEnd); } sqlite3KeyInfoUnref(pKeyDup); /* Generate a subroutine to run when the results from select A ** are exhausted and only data in select B remains. */ if( op==TK_EXCEPT || op==TK_INTERSECT ){ addrEofA_noB = addrEofA = labelEnd; }else{ VdbeNoopComment((v, "eof-A subroutine")); addrEofA = sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB); addrEofA_noB = sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, labelEnd); VdbeCoverage(v); sqlite3VdbeGoto(v, addrEofA); p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow); } /* Generate a subroutine to run when the results from select B ** are exhausted and only data in select A remains. */ if( op==TK_INTERSECT ){ addrEofB = addrEofA; if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow; }else{ VdbeNoopComment((v, "eof-B subroutine")); addrEofB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA); sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, labelEnd); VdbeCoverage(v); sqlite3VdbeGoto(v, addrEofB); } /* Generate code to handle the case of AB */ VdbeNoopComment((v, "A-gt-B subroutine")); addrAgtB = sqlite3VdbeCurrentAddr(v); if( op==TK_ALL || op==TK_UNION ){ sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB); } sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v); sqlite3VdbeGoto(v, labelCmpr); /* This code runs once to initialize everything. */ sqlite3VdbeJumpHere(v, addr1); sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA_noB); VdbeCoverage(v); sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v); /* Implement the main merge loop */ sqlite3VdbeResolveLabel(v, labelCmpr); sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY); sqlite3VdbeAddOp4(v, OP_Compare, destA.iSdst, destB.iSdst, nOrderBy, (char*)pKeyMerge, P4_KEYINFO); sqlite3VdbeChangeP5(v, OPFLAG_PERMUTE); sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB); VdbeCoverage(v); /* Jump to the this point in order to terminate the query. */ sqlite3VdbeResolveLabel(v, labelEnd); /* Set the number of output columns */ if( pDest->eDest==SRT_Output ){ Select *pFirst = pPrior; while( pFirst->pPrior ) pFirst = pFirst->pPrior; generateColumnNames(pParse, pFirst->pSrc, pFirst->pEList); } /* Reassembly the compound query so that it will be freed correctly ** by the calling function */ if( p->pPrior ){ sqlite3SelectDelete(db, p->pPrior); } p->pPrior = pPrior; pPrior->pNext = p; /*** TBD: Insert subroutine calls to close cursors on incomplete **** subqueries ****/ explainComposite(pParse, p->op, iSub1, iSub2, 0); return pParse->nErr!=0; } #endif #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) /* Forward Declarations */ static void substExprList(sqlite3*, ExprList*, int, ExprList*); static void substSelect(sqlite3*, Select *, int, ExprList*, int); /* ** Scan through the expression pExpr. Replace every reference to ** a column in table number iTable with a copy of the iColumn-th ** entry in pEList. (But leave references to the ROWID column ** unchanged.) ** ** This routine is part of the flattening procedure. A subquery ** whose result set is defined by pEList appears as entry in the ** FROM clause of a SELECT such that the VDBE cursor assigned to that ** FORM clause entry is iTable. This routine make the necessary ** changes to pExpr so that it refers directly to the source table ** of the subquery rather the result set of the subquery. */ static Expr *substExpr( sqlite3 *db, /* Report malloc errors to this connection */ Expr *pExpr, /* Expr in which substitution occurs */ int iTable, /* Table to be substituted */ ExprList *pEList /* Substitute expressions */ ){ if( pExpr==0 ) return 0; if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){ if( pExpr->iColumn<0 ){ pExpr->op = TK_NULL; }else{ Expr *pNew; assert( pEList!=0 && pExpr->iColumnnExpr ); assert( pExpr->pLeft==0 && pExpr->pRight==0 ); pNew = sqlite3ExprDup(db, pEList->a[pExpr->iColumn].pExpr, 0); sqlite3ExprDelete(db, pExpr); pExpr = pNew; } }else{ pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList); pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList); if( ExprHasProperty(pExpr, EP_xIsSelect) ){ substSelect(db, pExpr->x.pSelect, iTable, pEList, 1); }else{ substExprList(db, pExpr->x.pList, iTable, pEList); } } return pExpr; } static void substExprList( sqlite3 *db, /* Report malloc errors here */ ExprList *pList, /* List to scan and in which to make substitutes */ int iTable, /* Table to be substituted */ ExprList *pEList /* Substitute values */ ){ int i; if( pList==0 ) return; for(i=0; inExpr; i++){ pList->a[i].pExpr = substExpr(db, pList->a[i].pExpr, iTable, pEList); } } static void substSelect( sqlite3 *db, /* Report malloc errors here */ Select *p, /* SELECT statement in which to make substitutions */ int iTable, /* Table to be replaced */ ExprList *pEList, /* Substitute values */ int doPrior /* Do substitutes on p->pPrior too */ ){ SrcList *pSrc; struct SrcList_item *pItem; int i; if( !p ) return; do{ substExprList(db, p->pEList, iTable, pEList); substExprList(db, p->pGroupBy, iTable, pEList); substExprList(db, p->pOrderBy, iTable, pEList); p->pHaving = substExpr(db, p->pHaving, iTable, pEList); p->pWhere = substExpr(db, p->pWhere, iTable, pEList); pSrc = p->pSrc; assert( pSrc!=0 ); for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ substSelect(db, pItem->pSelect, iTable, pEList, 1); if( pItem->fg.isTabFunc ){ substExprList(db, pItem->u1.pFuncArg, iTable, pEList); } } }while( doPrior && (p = p->pPrior)!=0 ); } #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) /* ** This routine attempts to flatten subqueries as a performance optimization. ** This routine returns 1 if it makes changes and 0 if no flattening occurs. ** ** To understand the concept of flattening, consider the following ** query: ** ** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5 ** ** The default way of implementing this query is to execute the ** subquery first and store the results in a temporary table, then ** run the outer query on that temporary table. This requires two ** passes over the data. Furthermore, because the temporary table ** has no indices, the WHERE clause on the outer query cannot be ** optimized. ** ** This routine attempts to rewrite queries such as the above into ** a single flat select, like this: ** ** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5 ** ** The code generated for this simplification gives the same result ** but only has to scan the data once. And because indices might ** exist on the table t1, a complete scan of the data might be ** avoided. ** ** Flattening is only attempted if all of the following are true: ** ** (1) The subquery and the outer query do not both use aggregates. ** ** (2) The subquery is not an aggregate or (2a) the outer query is not a join ** and (2b) the outer query does not use subqueries other than the one ** FROM-clause subquery that is a candidate for flattening. (2b is ** due to ticket [2f7170d73bf9abf80] from 2015-02-09.) ** ** (3) The subquery is not the right operand of a left outer join ** (Originally ticket #306. Strengthened by ticket #3300) ** ** (4) The subquery is not DISTINCT. ** ** (**) At one point restrictions (4) and (5) defined a subset of DISTINCT ** sub-queries that were excluded from this optimization. Restriction ** (4) has since been expanded to exclude all DISTINCT subqueries. ** ** (6) The subquery does not use aggregates or the outer query is not ** DISTINCT. ** ** (7) The subquery has a FROM clause. TODO: For subqueries without ** A FROM clause, consider adding a FROM close with the special ** table sqlite_once that consists of a single row containing a ** single NULL. ** ** (8) The subquery does not use LIMIT or the outer query is not a join. ** ** (9) The subquery does not use LIMIT or the outer query does not use ** aggregates. ** ** (**) Restriction (10) was removed from the code on 2005-02-05 but we ** accidently carried the comment forward until 2014-09-15. Original ** text: "The subquery does not use aggregates or the outer query ** does not use LIMIT." ** ** (11) The subquery and the outer query do not both have ORDER BY clauses. ** ** (**) Not implemented. Subsumed into restriction (3). Was previously ** a separate restriction deriving from ticket #350. ** ** (13) The subquery and outer query do not both use LIMIT. ** ** (14) The subquery does not use OFFSET. ** ** (15) The outer query is not part of a compound select or the ** subquery does not have a LIMIT clause. ** (See ticket #2339 and ticket [02a8e81d44]). ** ** (16) The outer query is not an aggregate or the subquery does ** not contain ORDER BY. (Ticket #2942) This used to not matter ** until we introduced the group_concat() function. ** ** (17) The sub-query is not a compound select, or it is a UNION ALL ** compound clause made up entirely of non-aggregate queries, and ** the parent query: ** ** * is not itself part of a compound select, ** * is not an aggregate or DISTINCT query, and ** * is not a join ** ** The parent and sub-query may contain WHERE clauses. Subject to ** rules (11), (13) and (14), they may also contain ORDER BY, ** LIMIT and OFFSET clauses. The subquery cannot use any compound ** operator other than UNION ALL because all the other compound ** operators have an implied DISTINCT which is disallowed by ** restriction (4). ** ** Also, each component of the sub-query must return the same number ** of result columns. This is actually a requirement for any compound ** SELECT statement, but all the code here does is make sure that no ** such (illegal) sub-query is flattened. The caller will detect the ** syntax error and return a detailed message. ** ** (18) If the sub-query is a compound select, then all terms of the ** ORDER by clause of the parent must be simple references to ** columns of the sub-query. ** ** (19) The subquery does not use LIMIT or the outer query does not ** have a WHERE clause. ** ** (20) If the sub-query is a compound select, then it must not use ** an ORDER BY clause. Ticket #3773. We could relax this constraint ** somewhat by saying that the terms of the ORDER BY clause must ** appear as unmodified result columns in the outer query. But we ** have other optimizations in mind to deal with that case. ** ** (21) The subquery does not use LIMIT or the outer query is not ** DISTINCT. (See ticket [752e1646fc]). ** ** (22) The subquery is not a recursive CTE. ** ** (23) The parent is not a recursive CTE, or the sub-query is not a ** compound query. This restriction is because transforming the ** parent to a compound query confuses the code that handles ** recursive queries in multiSelect(). ** ** (24) The subquery is not an aggregate that uses the built-in min() or ** or max() functions. (Without this restriction, a query like: ** "SELECT x FROM (SELECT max(y), x FROM t1)" would not necessarily ** return the value X for which Y was maximal.) ** ** ** In this routine, the "p" parameter is a pointer to the outer query. ** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query ** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates. ** ** If flattening is not attempted, this routine is a no-op and returns 0. ** If flattening is attempted this routine returns 1. ** ** All of the expression analysis must occur on both the outer query and ** the subquery before this routine runs. */ static int flattenSubquery( Parse *pParse, /* Parsing context */ Select *p, /* The parent or outer SELECT statement */ int iFrom, /* Index in p->pSrc->a[] of the inner subquery */ int isAgg, /* True if outer SELECT uses aggregate functions */ int subqueryIsAgg /* True if the subquery uses aggregate functions */ ){ const char *zSavedAuthContext = pParse->zAuthContext; Select *pParent; /* Current UNION ALL term of the other query */ Select *pSub; /* The inner query or "subquery" */ Select *pSub1; /* Pointer to the rightmost select in sub-query */ SrcList *pSrc; /* The FROM clause of the outer query */ SrcList *pSubSrc; /* The FROM clause of the subquery */ ExprList *pList; /* The result set of the outer query */ int iParent; /* VDBE cursor number of the pSub result set temp table */ int i; /* Loop counter */ Expr *pWhere; /* The WHERE clause */ struct SrcList_item *pSubitem; /* The subquery */ sqlite3 *db = pParse->db; /* Check to see if flattening is permitted. Return 0 if not. */ assert( p!=0 ); assert( p->pPrior==0 ); /* Unable to flatten compound queries */ if( OptimizationDisabled(db, SQLITE_QueryFlattener) ) return 0; pSrc = p->pSrc; assert( pSrc && iFrom>=0 && iFromnSrc ); pSubitem = &pSrc->a[iFrom]; iParent = pSubitem->iCursor; pSub = pSubitem->pSelect; assert( pSub!=0 ); if( subqueryIsAgg ){ if( isAgg ) return 0; /* Restriction (1) */ if( pSrc->nSrc>1 ) return 0; /* Restriction (2a) */ if( (p->pWhere && ExprHasProperty(p->pWhere,EP_Subquery)) || (sqlite3ExprListFlags(p->pEList) & EP_Subquery)!=0 || (sqlite3ExprListFlags(p->pOrderBy) & EP_Subquery)!=0 ){ return 0; /* Restriction (2b) */ } } pSubSrc = pSub->pSrc; assert( pSubSrc ); /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants, ** not arbitrary expressions, we allowed some combining of LIMIT and OFFSET ** because they could be computed at compile-time. But when LIMIT and OFFSET ** became arbitrary expressions, we were forced to add restrictions (13) ** and (14). */ if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */ if( pSub->pOffset ) return 0; /* Restriction (14) */ if( (p->selFlags & SF_Compound)!=0 && pSub->pLimit ){ return 0; /* Restriction (15) */ } if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */ if( pSub->selFlags & SF_Distinct ) return 0; /* Restriction (5) */ if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){ return 0; /* Restrictions (8)(9) */ } if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){ return 0; /* Restriction (6) */ } if( p->pOrderBy && pSub->pOrderBy ){ return 0; /* Restriction (11) */ } if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */ if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */ if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){ return 0; /* Restriction (21) */ } testcase( pSub->selFlags & SF_Recursive ); testcase( pSub->selFlags & SF_MinMaxAgg ); if( pSub->selFlags & (SF_Recursive|SF_MinMaxAgg) ){ return 0; /* Restrictions (22) and (24) */ } if( (p->selFlags & SF_Recursive) && pSub->pPrior ){ return 0; /* Restriction (23) */ } /* OBSOLETE COMMENT 1: ** Restriction 3: If the subquery is a join, make sure the subquery is ** not used as the right operand of an outer join. Examples of why this ** is not allowed: ** ** t1 LEFT OUTER JOIN (t2 JOIN t3) ** ** If we flatten the above, we would get ** ** (t1 LEFT OUTER JOIN t2) JOIN t3 ** ** which is not at all the same thing. ** ** OBSOLETE COMMENT 2: ** Restriction 12: If the subquery is the right operand of a left outer ** join, make sure the subquery has no WHERE clause. ** An examples of why this is not allowed: ** ** t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0) ** ** If we flatten the above, we would get ** ** (t1 LEFT OUTER JOIN t2) WHERE t2.x>0 ** ** But the t2.x>0 test will always fail on a NULL row of t2, which ** effectively converts the OUTER JOIN into an INNER JOIN. ** ** THIS OVERRIDES OBSOLETE COMMENTS 1 AND 2 ABOVE: ** Ticket #3300 shows that flattening the right term of a LEFT JOIN ** is fraught with danger. Best to avoid the whole thing. If the ** subquery is the right term of a LEFT JOIN, then do not flatten. */ if( (pSubitem->fg.jointype & JT_OUTER)!=0 ){ return 0; } /* Restriction 17: If the sub-query is a compound SELECT, then it must ** use only the UNION ALL operator. And none of the simple select queries ** that make up the compound SELECT are allowed to be aggregate or distinct ** queries. */ if( pSub->pPrior ){ if( pSub->pOrderBy ){ return 0; /* Restriction 20 */ } if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){ return 0; } for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){ testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct ); testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate ); assert( pSub->pSrc!=0 ); assert( pSub->pEList->nExpr==pSub1->pEList->nExpr ); if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0 || (pSub1->pPrior && pSub1->op!=TK_ALL) || pSub1->pSrc->nSrc<1 ){ return 0; } testcase( pSub1->pSrc->nSrc>1 ); } /* Restriction 18. */ if( p->pOrderBy ){ int ii; for(ii=0; iipOrderBy->nExpr; ii++){ if( p->pOrderBy->a[ii].u.x.iOrderByCol==0 ) return 0; } } } /***** If we reach this point, flattening is permitted. *****/ SELECTTRACE(1,pParse,p,("flatten %s.%p from term %d\n", pSub->zSelName, pSub, iFrom)); /* Authorize the subquery */ pParse->zAuthContext = pSubitem->zName; TESTONLY(i =) sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0); testcase( i==SQLITE_DENY ); pParse->zAuthContext = zSavedAuthContext; /* If the sub-query is a compound SELECT statement, then (by restrictions ** 17 and 18 above) it must be a UNION ALL and the parent query must ** be of the form: ** ** SELECT FROM () ** ** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block ** creates N-1 copies of the parent query without any ORDER BY, LIMIT or ** OFFSET clauses and joins them to the left-hand-side of the original ** using UNION ALL operators. In this case N is the number of simple ** select statements in the compound sub-query. ** ** Example: ** ** SELECT a+1 FROM ( ** SELECT x FROM tab ** UNION ALL ** SELECT y FROM tab ** UNION ALL ** SELECT abs(z*2) FROM tab2 ** ) WHERE a!=5 ORDER BY 1 ** ** Transformed into: ** ** SELECT x+1 FROM tab WHERE x+1!=5 ** UNION ALL ** SELECT y+1 FROM tab WHERE y+1!=5 ** UNION ALL ** SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5 ** ORDER BY 1 ** ** We call this the "compound-subquery flattening". */ for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){ Select *pNew; ExprList *pOrderBy = p->pOrderBy; Expr *pLimit = p->pLimit; Expr *pOffset = p->pOffset; Select *pPrior = p->pPrior; p->pOrderBy = 0; p->pSrc = 0; p->pPrior = 0; p->pLimit = 0; p->pOffset = 0; pNew = sqlite3SelectDup(db, p, 0); sqlite3SelectSetName(pNew, pSub->zSelName); p->pOffset = pOffset; p->pLimit = pLimit; p->pOrderBy = pOrderBy; p->pSrc = pSrc; p->op = TK_ALL; if( pNew==0 ){ p->pPrior = pPrior; }else{ pNew->pPrior = pPrior; if( pPrior ) pPrior->pNext = pNew; pNew->pNext = p; p->pPrior = pNew; SELECTTRACE(2,pParse,p, ("compound-subquery flattener creates %s.%p as peer\n", pNew->zSelName, pNew)); } if( db->mallocFailed ) return 1; } /* Begin flattening the iFrom-th entry of the FROM clause ** in the outer query. */ pSub = pSub1 = pSubitem->pSelect; /* Delete the transient table structure associated with the ** subquery */ sqlite3DbFree(db, pSubitem->zDatabase); sqlite3DbFree(db, pSubitem->zName); sqlite3DbFree(db, pSubitem->zAlias); pSubitem->zDatabase = 0; pSubitem->zName = 0; pSubitem->zAlias = 0; pSubitem->pSelect = 0; /* Defer deleting the Table object associated with the ** subquery until code generation is ** complete, since there may still exist Expr.pTab entries that ** refer to the subquery even after flattening. Ticket #3346. ** ** pSubitem->pTab is always non-NULL by test restrictions and tests above. */ if( ALWAYS(pSubitem->pTab!=0) ){ Table *pTabToDel = pSubitem->pTab; if( pTabToDel->nRef==1 ){ Parse *pToplevel = sqlite3ParseToplevel(pParse); pTabToDel->pNextZombie = pToplevel->pZombieTab; pToplevel->pZombieTab = pTabToDel; }else{ pTabToDel->nRef--; } pSubitem->pTab = 0; } /* The following loop runs once for each term in a compound-subquery ** flattening (as described above). If we are doing a different kind ** of flattening - a flattening other than a compound-subquery flattening - ** then this loop only runs once. ** ** This loop moves all of the FROM elements of the subquery into the ** the FROM clause of the outer query. Before doing this, remember ** the cursor number for the original outer query FROM element in ** iParent. The iParent cursor will never be used. Subsequent code ** will scan expressions looking for iParent references and replace ** those references with expressions that resolve to the subquery FROM ** elements we are now copying in. */ for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){ int nSubSrc; u8 jointype = 0; pSubSrc = pSub->pSrc; /* FROM clause of subquery */ nSubSrc = pSubSrc->nSrc; /* Number of terms in subquery FROM clause */ pSrc = pParent->pSrc; /* FROM clause of the outer query */ if( pSrc ){ assert( pParent==p ); /* First time through the loop */ jointype = pSubitem->fg.jointype; }else{ assert( pParent!=p ); /* 2nd and subsequent times through the loop */ pSrc = pParent->pSrc = sqlite3SrcListAppend(db, 0, 0, 0); if( pSrc==0 ){ assert( db->mallocFailed ); break; } } /* The subquery uses a single slot of the FROM clause of the outer ** query. If the subquery has more than one element in its FROM clause, ** then expand the outer query to make space for it to hold all elements ** of the subquery. ** ** Example: ** ** SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB; ** ** The outer query has 3 slots in its FROM clause. One slot of the ** outer query (the middle slot) is used by the subquery. The next ** block of code will expand the outer query FROM clause to 4 slots. ** The middle slot is expanded to two slots in order to make space ** for the two elements in the FROM clause of the subquery. */ if( nSubSrc>1 ){ pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1); if( db->mallocFailed ){ break; } } /* Transfer the FROM clause terms from the subquery into the ** outer query. */ for(i=0; ia[i+iFrom].pUsing); assert( pSrc->a[i+iFrom].fg.isTabFunc==0 ); pSrc->a[i+iFrom] = pSubSrc->a[i]; memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i])); } pSrc->a[iFrom].fg.jointype = jointype; /* Now begin substituting subquery result set expressions for ** references to the iParent in the outer query. ** ** Example: ** ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b; ** \ \_____________ subquery __________/ / ** \_____________________ outer query ______________________________/ ** ** We look at every expression in the outer query and every place we see ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10". */ pList = pParent->pEList; for(i=0; inExpr; i++){ if( pList->a[i].zName==0 ){ char *zName = sqlite3DbStrDup(db, pList->a[i].zSpan); sqlite3Dequote(zName); pList->a[i].zName = zName; } } if( pSub->pOrderBy ){ /* At this point, any non-zero iOrderByCol values indicate that the ** ORDER BY column expression is identical to the iOrderByCol'th ** expression returned by SELECT statement pSub. Since these values ** do not necessarily correspond to columns in SELECT statement pParent, ** zero them before transfering the ORDER BY clause. ** ** Not doing this may cause an error if a subsequent call to this ** function attempts to flatten a compound sub-query into pParent ** (the only way this can happen is if the compound sub-query is ** currently part of pSub->pSrc). See ticket [d11a6e908f]. */ ExprList *pOrderBy = pSub->pOrderBy; for(i=0; inExpr; i++){ pOrderBy->a[i].u.x.iOrderByCol = 0; } assert( pParent->pOrderBy==0 ); assert( pSub->pPrior==0 ); pParent->pOrderBy = pOrderBy; pSub->pOrderBy = 0; } pWhere = sqlite3ExprDup(db, pSub->pWhere, 0); if( subqueryIsAgg ){ assert( pParent->pHaving==0 ); pParent->pHaving = pParent->pWhere; pParent->pWhere = pWhere; pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving, sqlite3ExprDup(db, pSub->pHaving, 0)); assert( pParent->pGroupBy==0 ); pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0); }else{ pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere); } substSelect(db, pParent, iParent, pSub->pEList, 0); /* The flattened query is distinct if either the inner or the ** outer query is distinct. */ pParent->selFlags |= pSub->selFlags & SF_Distinct; /* ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y; ** ** One is tempted to try to add a and b to combine the limits. But this ** does not work if either limit is negative. */ if( pSub->pLimit ){ pParent->pLimit = pSub->pLimit; pSub->pLimit = 0; } } /* Finially, delete what is left of the subquery and return ** success. */ sqlite3SelectDelete(db, pSub1); #if SELECTTRACE_ENABLED if( sqlite3SelectTrace & 0x100 ){ SELECTTRACE(0x100,pParse,p,("After flattening:\n")); sqlite3TreeViewSelect(0, p, 0); } #endif return 1; } #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) /* ** Make copies of relevant WHERE clause terms of the outer query into ** the WHERE clause of subquery. Example: ** ** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1) WHERE x=5 AND y=10; ** ** Transformed into: ** ** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1 WHERE a=5 AND c-d=10) ** WHERE x=5 AND y=10; ** ** The hope is that the terms added to the inner query will make it more ** efficient. ** ** Do not attempt this optimization if: ** ** (1) The inner query is an aggregate. (In that case, we'd really want ** to copy the outer WHERE-clause terms onto the HAVING clause of the ** inner query. But they probably won't help there so do not bother.) ** ** (2) The inner query is the recursive part of a common table expression. ** ** (3) The inner query has a LIMIT clause (since the changes to the WHERE ** close would change the meaning of the LIMIT). ** ** (4) The inner query is the right operand of a LEFT JOIN. (The caller ** enforces this restriction since this routine does not have enough ** information to know.) ** ** (5) The WHERE clause expression originates in the ON or USING clause ** of a LEFT JOIN. ** ** Return 0 if no changes are made and non-zero if one or more WHERE clause ** terms are duplicated into the subquery. */ static int pushDownWhereTerms( sqlite3 *db, /* The database connection (for malloc()) */ Select *pSubq, /* The subquery whose WHERE clause is to be augmented */ Expr *pWhere, /* The WHERE clause of the outer query */ int iCursor /* Cursor number of the subquery */ ){ Expr *pNew; int nChng = 0; Select *pX; /* For looping over compound SELECTs in pSubq */ if( pWhere==0 ) return 0; for(pX=pSubq; pX; pX=pX->pPrior){ if( (pX->selFlags & (SF_Aggregate|SF_Recursive))!=0 ){ testcase( pX->selFlags & SF_Aggregate ); testcase( pX->selFlags & SF_Recursive ); testcase( pX!=pSubq ); return 0; /* restrictions (1) and (2) */ } } if( pSubq->pLimit!=0 ){ return 0; /* restriction (3) */ } while( pWhere->op==TK_AND ){ nChng += pushDownWhereTerms(db, pSubq, pWhere->pRight, iCursor); pWhere = pWhere->pLeft; } if( ExprHasProperty(pWhere,EP_FromJoin) ) return 0; /* restriction 5 */ if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){ nChng++; while( pSubq ){ pNew = sqlite3ExprDup(db, pWhere, 0); pNew = substExpr(db, pNew, iCursor, pSubq->pEList); pSubq->pWhere = sqlite3ExprAnd(db, pSubq->pWhere, pNew); pSubq = pSubq->pPrior; } } return nChng; } #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ /* ** Based on the contents of the AggInfo structure indicated by the first ** argument, this function checks if the following are true: ** ** * the query contains just a single aggregate function, ** * the aggregate function is either min() or max(), and ** * the argument to the aggregate function is a column value. ** ** If all of the above are true, then WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX ** is returned as appropriate. Also, *ppMinMax is set to point to the ** list of arguments passed to the aggregate before returning. ** ** Or, if the conditions above are not met, *ppMinMax is set to 0 and ** WHERE_ORDERBY_NORMAL is returned. */ static u8 minMaxQuery(AggInfo *pAggInfo, ExprList **ppMinMax){ int eRet = WHERE_ORDERBY_NORMAL; /* Return value */ *ppMinMax = 0; if( pAggInfo->nFunc==1 ){ Expr *pExpr = pAggInfo->aFunc[0].pExpr; /* Aggregate function */ ExprList *pEList = pExpr->x.pList; /* Arguments to agg function */ assert( pExpr->op==TK_AGG_FUNCTION ); if( pEList && pEList->nExpr==1 && pEList->a[0].pExpr->op==TK_AGG_COLUMN ){ const char *zFunc = pExpr->u.zToken; if( sqlite3StrICmp(zFunc, "min")==0 ){ eRet = WHERE_ORDERBY_MIN; *ppMinMax = pEList; }else if( sqlite3StrICmp(zFunc, "max")==0 ){ eRet = WHERE_ORDERBY_MAX; *ppMinMax = pEList; } } } assert( *ppMinMax==0 || (*ppMinMax)->nExpr==1 ); return eRet; } /* ** The select statement passed as the first argument is an aggregate query. ** The second argument is the associated aggregate-info object. This ** function tests if the SELECT is of the form: ** ** SELECT count(*) FROM ** ** where table is a database table, not a sub-select or view. If the query ** does match this pattern, then a pointer to the Table object representing ** is returned. Otherwise, 0 is returned. */ static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){ Table *pTab; Expr *pExpr; assert( !p->pGroupBy ); if( p->pWhere || p->pEList->nExpr!=1 || p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect ){ return 0; } pTab = p->pSrc->a[0].pTab; pExpr = p->pEList->a[0].pExpr; assert( pTab && !pTab->pSelect && pExpr ); if( IsVirtual(pTab) ) return 0; if( pExpr->op!=TK_AGG_FUNCTION ) return 0; if( NEVER(pAggInfo->nFunc==0) ) return 0; if( (pAggInfo->aFunc[0].pFunc->funcFlags&SQLITE_FUNC_COUNT)==0 ) return 0; if( pExpr->flags&EP_Distinct ) return 0; return pTab; } /* ** If the source-list item passed as an argument was augmented with an ** INDEXED BY clause, then try to locate the specified index. If there ** was such a clause and the named index cannot be found, return ** SQLITE_ERROR and leave an error in pParse. Otherwise, populate ** pFrom->pIndex and return SQLITE_OK. */ int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){ if( pFrom->pTab && pFrom->fg.isIndexedBy ){ Table *pTab = pFrom->pTab; char *zIndexedBy = pFrom->u1.zIndexedBy; Index *pIdx; for(pIdx=pTab->pIndex; pIdx && sqlite3StrICmp(pIdx->zName, zIndexedBy); pIdx=pIdx->pNext ); if( !pIdx ){ sqlite3ErrorMsg(pParse, "no such index: %s", zIndexedBy, 0); pParse->checkSchema = 1; return SQLITE_ERROR; } pFrom->pIBIndex = pIdx; } return SQLITE_OK; } /* ** Detect compound SELECT statements that use an ORDER BY clause with ** an alternative collating sequence. ** ** SELECT ... FROM t1 EXCEPT SELECT ... FROM t2 ORDER BY .. COLLATE ... ** ** These are rewritten as a subquery: ** ** SELECT * FROM (SELECT ... FROM t1 EXCEPT SELECT ... FROM t2) ** ORDER BY ... COLLATE ... ** ** This transformation is necessary because the multiSelectOrderBy() routine ** above that generates the code for a compound SELECT with an ORDER BY clause ** uses a merge algorithm that requires the same collating sequence on the ** result columns as on the ORDER BY clause. See ticket ** http://www.sqlite.org/src/info/6709574d2a ** ** This transformation is only needed for EXCEPT, INTERSECT, and UNION. ** The UNION ALL operator works fine with multiSelectOrderBy() even when ** there are COLLATE terms in the ORDER BY. */ static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){ int i; Select *pNew; Select *pX; sqlite3 *db; struct ExprList_item *a; SrcList *pNewSrc; Parse *pParse; Token dummy; if( p->pPrior==0 ) return WRC_Continue; if( p->pOrderBy==0 ) return WRC_Continue; for(pX=p; pX && (pX->op==TK_ALL || pX->op==TK_SELECT); pX=pX->pPrior){} if( pX==0 ) return WRC_Continue; a = p->pOrderBy->a; for(i=p->pOrderBy->nExpr-1; i>=0; i--){ if( a[i].pExpr->flags & EP_Collate ) break; } if( i<0 ) return WRC_Continue; /* If we reach this point, that means the transformation is required. */ pParse = pWalker->pParse; db = pParse->db; pNew = sqlite3DbMallocZero(db, sizeof(*pNew) ); if( pNew==0 ) return WRC_Abort; memset(&dummy, 0, sizeof(dummy)); pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0,0); if( pNewSrc==0 ) return WRC_Abort; *pNew = *p; p->pSrc = pNewSrc; p->pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ASTERISK, 0)); p->op = TK_SELECT; p->pWhere = 0; pNew->pGroupBy = 0; pNew->pHaving = 0; pNew->pOrderBy = 0; p->pPrior = 0; p->pNext = 0; p->pWith = 0; p->selFlags &= ~SF_Compound; assert( (p->selFlags & SF_Converted)==0 ); p->selFlags |= SF_Converted; assert( pNew->pPrior!=0 ); pNew->pPrior->pNext = pNew; pNew->pLimit = 0; pNew->pOffset = 0; return WRC_Continue; } /* ** Check to see if the FROM clause term pFrom has table-valued function ** arguments. If it does, leave an error message in pParse and return ** non-zero, since pFrom is not allowed to be a table-valued function. */ static int cannotBeFunction(Parse *pParse, struct SrcList_item *pFrom){ if( pFrom->fg.isTabFunc ){ sqlite3ErrorMsg(pParse, "'%s' is not a function", pFrom->zName); return 1; } return 0; } #ifndef SQLITE_OMIT_CTE /* ** Argument pWith (which may be NULL) points to a linked list of nested ** WITH contexts, from inner to outermost. If the table identified by ** FROM clause element pItem is really a common-table-expression (CTE) ** then return a pointer to the CTE definition for that table. Otherwise ** return NULL. ** ** If a non-NULL value is returned, set *ppContext to point to the With ** object that the returned CTE belongs to. */ static struct Cte *searchWith( With *pWith, /* Current innermost WITH clause */ struct SrcList_item *pItem, /* FROM clause element to resolve */ With **ppContext /* OUT: WITH clause return value belongs to */ ){ const char *zName; if( pItem->zDatabase==0 && (zName = pItem->zName)!=0 ){ With *p; for(p=pWith; p; p=p->pOuter){ int i; for(i=0; inCte; i++){ if( sqlite3StrICmp(zName, p->a[i].zName)==0 ){ *ppContext = p; return &p->a[i]; } } } } return 0; } /* The code generator maintains a stack of active WITH clauses ** with the inner-most WITH clause being at the top of the stack. ** ** This routine pushes the WITH clause passed as the second argument ** onto the top of the stack. If argument bFree is true, then this ** WITH clause will never be popped from the stack. In this case it ** should be freed along with the Parse object. In other cases, when ** bFree==0, the With object will be freed along with the SELECT ** statement with which it is associated. */ void sqlite3WithPush(Parse *pParse, With *pWith, u8 bFree){ assert( bFree==0 || (pParse->pWith==0 && pParse->pWithToFree==0) ); if( pWith ){ assert( pParse->pWith!=pWith ); pWith->pOuter = pParse->pWith; pParse->pWith = pWith; if( bFree ) pParse->pWithToFree = pWith; } } /* ** This function checks if argument pFrom refers to a CTE declared by ** a WITH clause on the stack currently maintained by the parser. And, ** if currently processing a CTE expression, if it is a recursive ** reference to the current CTE. ** ** If pFrom falls into either of the two categories above, pFrom->pTab ** and other fields are populated accordingly. The caller should check ** (pFrom->pTab!=0) to determine whether or not a successful match ** was found. ** ** Whether or not a match is found, SQLITE_OK is returned if no error ** occurs. If an error does occur, an error message is stored in the ** parser and some error code other than SQLITE_OK returned. */ static int withExpand( Walker *pWalker, struct SrcList_item *pFrom ){ Parse *pParse = pWalker->pParse; sqlite3 *db = pParse->db; struct Cte *pCte; /* Matched CTE (or NULL if no match) */ With *pWith; /* WITH clause that pCte belongs to */ assert( pFrom->pTab==0 ); pCte = searchWith(pParse->pWith, pFrom, &pWith); if( pCte ){ Table *pTab; ExprList *pEList; Select *pSel; Select *pLeft; /* Left-most SELECT statement */ int bMayRecursive; /* True if compound joined by UNION [ALL] */ With *pSavedWith; /* Initial value of pParse->pWith */ /* If pCte->zCteErr is non-NULL at this point, then this is an illegal ** recursive reference to CTE pCte. Leave an error in pParse and return ** early. If pCte->zCteErr is NULL, then this is not a recursive reference. ** In this case, proceed. */ if( pCte->zCteErr ){ sqlite3ErrorMsg(pParse, pCte->zCteErr, pCte->zName); return SQLITE_ERROR; } if( cannotBeFunction(pParse, pFrom) ) return SQLITE_ERROR; assert( pFrom->pTab==0 ); pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table)); if( pTab==0 ) return WRC_Abort; pTab->nRef = 1; pTab->zName = sqlite3DbStrDup(db, pCte->zName); pTab->iPKey = -1; pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) ); pTab->tabFlags |= TF_Ephemeral | TF_NoVisibleRowid; pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0); if( db->mallocFailed ) return SQLITE_NOMEM_BKPT; assert( pFrom->pSelect ); /* Check if this is a recursive CTE. */ pSel = pFrom->pSelect; bMayRecursive = ( pSel->op==TK_ALL || pSel->op==TK_UNION ); if( bMayRecursive ){ int i; SrcList *pSrc = pFrom->pSelect->pSrc; for(i=0; inSrc; i++){ struct SrcList_item *pItem = &pSrc->a[i]; if( pItem->zDatabase==0 && pItem->zName!=0 && 0==sqlite3StrICmp(pItem->zName, pCte->zName) ){ pItem->pTab = pTab; pItem->fg.isRecursive = 1; pTab->nRef++; pSel->selFlags |= SF_Recursive; } } } /* Only one recursive reference is permitted. */ if( pTab->nRef>2 ){ sqlite3ErrorMsg( pParse, "multiple references to recursive table: %s", pCte->zName ); return SQLITE_ERROR; } assert( pTab->nRef==1 || ((pSel->selFlags&SF_Recursive) && pTab->nRef==2 )); pCte->zCteErr = "circular reference: %s"; pSavedWith = pParse->pWith; pParse->pWith = pWith; sqlite3WalkSelect(pWalker, bMayRecursive ? pSel->pPrior : pSel); pParse->pWith = pWith; for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior); pEList = pLeft->pEList; if( pCte->pCols ){ if( pEList && pEList->nExpr!=pCte->pCols->nExpr ){ sqlite3ErrorMsg(pParse, "table %s has %d values for %d columns", pCte->zName, pEList->nExpr, pCte->pCols->nExpr ); pParse->pWith = pSavedWith; return SQLITE_ERROR; } pEList = pCte->pCols; } sqlite3ColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol); if( bMayRecursive ){ if( pSel->selFlags & SF_Recursive ){ pCte->zCteErr = "multiple recursive references: %s"; }else{ pCte->zCteErr = "recursive reference in a subquery: %s"; } sqlite3WalkSelect(pWalker, pSel); } pCte->zCteErr = 0; pParse->pWith = pSavedWith; } return SQLITE_OK; } #endif #ifndef SQLITE_OMIT_CTE /* ** If the SELECT passed as the second argument has an associated WITH ** clause, pop it from the stack stored as part of the Parse object. ** ** This function is used as the xSelectCallback2() callback by ** sqlite3SelectExpand() when walking a SELECT tree to resolve table ** names and other FROM clause elements. */ static void selectPopWith(Walker *pWalker, Select *p){ Parse *pParse = pWalker->pParse; With *pWith = findRightmost(p)->pWith; if( pWith!=0 ){ assert( pParse->pWith==pWith ); pParse->pWith = pWith->pOuter; } } #else #define selectPopWith 0 #endif /* ** This routine is a Walker callback for "expanding" a SELECT statement. ** "Expanding" means to do the following: ** ** (1) Make sure VDBE cursor numbers have been assigned to every ** element of the FROM clause. ** ** (2) Fill in the pTabList->a[].pTab fields in the SrcList that ** defines FROM clause. When views appear in the FROM clause, ** fill pTabList->a[].pSelect with a copy of the SELECT statement ** that implements the view. A copy is made of the view's SELECT ** statement so that we can freely modify or delete that statement ** without worrying about messing up the persistent representation ** of the view. ** ** (3) Add terms to the WHERE clause to accommodate the NATURAL keyword ** on joins and the ON and USING clause of joins. ** ** (4) Scan the list of columns in the result set (pEList) looking ** for instances of the "*" operator or the TABLE.* operator. ** If found, expand each "*" to be every column in every table ** and TABLE.* to be every column in TABLE. ** */ static int selectExpander(Walker *pWalker, Select *p){ Parse *pParse = pWalker->pParse; int i, j, k; SrcList *pTabList; ExprList *pEList; struct SrcList_item *pFrom; sqlite3 *db = pParse->db; Expr *pE, *pRight, *pExpr; u16 selFlags = p->selFlags; p->selFlags |= SF_Expanded; if( db->mallocFailed ){ return WRC_Abort; } if( NEVER(p->pSrc==0) || (selFlags & SF_Expanded)!=0 ){ return WRC_Prune; } pTabList = p->pSrc; pEList = p->pEList; if( pWalker->xSelectCallback2==selectPopWith ){ sqlite3WithPush(pParse, findRightmost(p)->pWith, 0); } /* Make sure cursor numbers have been assigned to all entries in ** the FROM clause of the SELECT statement. */ sqlite3SrcListAssignCursors(pParse, pTabList); /* Look up every table named in the FROM clause of the select. If ** an entry of the FROM clause is a subquery instead of a table or view, ** then create a transient table structure to describe the subquery. */ for(i=0, pFrom=pTabList->a; inSrc; i++, pFrom++){ Table *pTab; assert( pFrom->fg.isRecursive==0 || pFrom->pTab!=0 ); if( pFrom->fg.isRecursive ) continue; assert( pFrom->pTab==0 ); #ifndef SQLITE_OMIT_CTE if( withExpand(pWalker, pFrom) ) return WRC_Abort; if( pFrom->pTab ) {} else #endif if( pFrom->zName==0 ){ #ifndef SQLITE_OMIT_SUBQUERY Select *pSel = pFrom->pSelect; /* A sub-query in the FROM clause of a SELECT */ assert( pSel!=0 ); assert( pFrom->pTab==0 ); if( sqlite3WalkSelect(pWalker, pSel) ) return WRC_Abort; pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table)); if( pTab==0 ) return WRC_Abort; pTab->nRef = 1; pTab->zName = sqlite3MPrintf(db, "sqlite_sq_%p", (void*)pTab); while( pSel->pPrior ){ pSel = pSel->pPrior; } sqlite3ColumnsFromExprList(pParse, pSel->pEList,&pTab->nCol,&pTab->aCol); pTab->iPKey = -1; pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) ); pTab->tabFlags |= TF_Ephemeral; #endif }else{ /* An ordinary table or view name in the FROM clause */ assert( pFrom->pTab==0 ); pFrom->pTab = pTab = sqlite3LocateTableItem(pParse, 0, pFrom); if( pTab==0 ) return WRC_Abort; if( pTab->nRef==0xffff ){ sqlite3ErrorMsg(pParse, "too many references to \"%s\": max 65535", pTab->zName); pFrom->pTab = 0; return WRC_Abort; } pTab->nRef++; if( !IsVirtual(pTab) && cannotBeFunction(pParse, pFrom) ){ return WRC_Abort; } #if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE) if( IsVirtual(pTab) || pTab->pSelect ){ i16 nCol; if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort; assert( pFrom->pSelect==0 ); pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0); sqlite3SelectSetName(pFrom->pSelect, pTab->zName); nCol = pTab->nCol; pTab->nCol = -1; sqlite3WalkSelect(pWalker, pFrom->pSelect); pTab->nCol = nCol; } #endif } /* Locate the index named by the INDEXED BY clause, if any. */ if( sqlite3IndexedByLookup(pParse, pFrom) ){ return WRC_Abort; } } /* Process NATURAL keywords, and ON and USING clauses of joins. */ if( db->mallocFailed || sqliteProcessJoin(pParse, p) ){ return WRC_Abort; } /* For every "*" that occurs in the column list, insert the names of ** all columns in all tables. And for every TABLE.* insert the names ** of all columns in TABLE. The parser inserted a special expression ** with the TK_ASTERISK operator for each "*" that it found in the column ** list. The following code just has to locate the TK_ASTERISK ** expressions and expand each one to the list of all columns in ** all tables. ** ** The first loop just checks to see if there are any "*" operators ** that need expanding. */ for(k=0; knExpr; k++){ pE = pEList->a[k].pExpr; if( pE->op==TK_ASTERISK ) break; assert( pE->op!=TK_DOT || pE->pRight!=0 ); assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) ); if( pE->op==TK_DOT && pE->pRight->op==TK_ASTERISK ) break; } if( knExpr ){ /* ** If we get here it means the result set contains one or more "*" ** operators that need to be expanded. Loop through each expression ** in the result set and expand them one by one. */ struct ExprList_item *a = pEList->a; ExprList *pNew = 0; int flags = pParse->db->flags; int longNames = (flags & SQLITE_FullColNames)!=0 && (flags & SQLITE_ShortColNames)==0; for(k=0; knExpr; k++){ pE = a[k].pExpr; pRight = pE->pRight; assert( pE->op!=TK_DOT || pRight!=0 ); if( pE->op!=TK_ASTERISK && (pE->op!=TK_DOT || pRight->op!=TK_ASTERISK) ){ /* This particular expression does not need to be expanded. */ pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr); if( pNew ){ pNew->a[pNew->nExpr-1].zName = a[k].zName; pNew->a[pNew->nExpr-1].zSpan = a[k].zSpan; a[k].zName = 0; a[k].zSpan = 0; } a[k].pExpr = 0; }else{ /* This expression is a "*" or a "TABLE.*" and needs to be ** expanded. */ int tableSeen = 0; /* Set to 1 when TABLE matches */ char *zTName = 0; /* text of name of TABLE */ if( pE->op==TK_DOT ){ assert( pE->pLeft!=0 ); assert( !ExprHasProperty(pE->pLeft, EP_IntValue) ); zTName = pE->pLeft->u.zToken; } for(i=0, pFrom=pTabList->a; inSrc; i++, pFrom++){ Table *pTab = pFrom->pTab; Select *pSub = pFrom->pSelect; char *zTabName = pFrom->zAlias; const char *zSchemaName = 0; int iDb; if( zTabName==0 ){ zTabName = pTab->zName; } if( db->mallocFailed ) break; if( pSub==0 || (pSub->selFlags & SF_NestedFrom)==0 ){ pSub = 0; if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){ continue; } iDb = sqlite3SchemaToIndex(db, pTab->pSchema); zSchemaName = iDb>=0 ? db->aDb[iDb].zDbSName : "*"; } for(j=0; jnCol; j++){ char *zName = pTab->aCol[j].zName; char *zColname; /* The computed column name */ char *zToFree; /* Malloced string that needs to be freed */ Token sColname; /* Computed column name as a token */ assert( zName ); if( zTName && pSub && sqlite3MatchSpanName(pSub->pEList->a[j].zSpan, 0, zTName, 0)==0 ){ continue; } /* If a column is marked as 'hidden', omit it from the expanded ** result-set list unless the SELECT has the SF_IncludeHidden ** bit set. */ if( (p->selFlags & SF_IncludeHidden)==0 && IsHiddenColumn(&pTab->aCol[j]) ){ continue; } tableSeen = 1; if( i>0 && zTName==0 ){ if( (pFrom->fg.jointype & JT_NATURAL)!=0 && tableAndColumnIndex(pTabList, i, zName, 0, 0) ){ /* In a NATURAL join, omit the join columns from the ** table to the right of the join */ continue; } if( sqlite3IdListIndex(pFrom->pUsing, zName)>=0 ){ /* In a join with a USING clause, omit columns in the ** using clause from the table on the right. */ continue; } } pRight = sqlite3Expr(db, TK_ID, zName); zColname = zName; zToFree = 0; if( longNames || pTabList->nSrc>1 ){ Expr *pLeft; pLeft = sqlite3Expr(db, TK_ID, zTabName); pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0); if( zSchemaName ){ pLeft = sqlite3Expr(db, TK_ID, zSchemaName); pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pExpr, 0); } if( longNames ){ zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName); zToFree = zColname; } }else{ pExpr = pRight; } pNew = sqlite3ExprListAppend(pParse, pNew, pExpr); sqlite3TokenInit(&sColname, zColname); sqlite3ExprListSetName(pParse, pNew, &sColname, 0); if( pNew && (p->selFlags & SF_NestedFrom)!=0 ){ struct ExprList_item *pX = &pNew->a[pNew->nExpr-1]; if( pSub ){ pX->zSpan = sqlite3DbStrDup(db, pSub->pEList->a[j].zSpan); testcase( pX->zSpan==0 ); }else{ pX->zSpan = sqlite3MPrintf(db, "%s.%s.%s", zSchemaName, zTabName, zColname); testcase( pX->zSpan==0 ); } pX->bSpanIsTab = 1; } sqlite3DbFree(db, zToFree); } } if( !tableSeen ){ if( zTName ){ sqlite3ErrorMsg(pParse, "no such table: %s", zTName); }else{ sqlite3ErrorMsg(pParse, "no tables specified"); } } } } sqlite3ExprListDelete(db, pEList); p->pEList = pNew; } #if SQLITE_MAX_COLUMN if( p->pEList && p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){ sqlite3ErrorMsg(pParse, "too many columns in result set"); return WRC_Abort; } #endif return WRC_Continue; } /* ** No-op routine for the parse-tree walker. ** ** When this routine is the Walker.xExprCallback then expression trees ** are walked without any actions being taken at each node. Presumably, ** when this routine is used for Walker.xExprCallback then ** Walker.xSelectCallback is set to do something useful for every ** subquery in the parser tree. */ int sqlite3ExprWalkNoop(Walker *NotUsed, Expr *NotUsed2){ UNUSED_PARAMETER2(NotUsed, NotUsed2); return WRC_Continue; } /* ** This routine "expands" a SELECT statement and all of its subqueries. ** For additional information on what it means to "expand" a SELECT ** statement, see the comment on the selectExpand worker callback above. ** ** Expanding a SELECT statement is the first step in processing a ** SELECT statement. The SELECT statement must be expanded before ** name resolution is performed. ** ** If anything goes wrong, an error message is written into pParse. ** The calling function can detect the problem by looking at pParse->nErr ** and/or pParse->db->mallocFailed. */ static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){ Walker w; memset(&w, 0, sizeof(w)); w.xExprCallback = sqlite3ExprWalkNoop; w.pParse = pParse; if( pParse->hasCompound ){ w.xSelectCallback = convertCompoundSelectToSubquery; sqlite3WalkSelect(&w, pSelect); } w.xSelectCallback = selectExpander; if( (pSelect->selFlags & SF_MultiValue)==0 ){ w.xSelectCallback2 = selectPopWith; } sqlite3WalkSelect(&w, pSelect); } #ifndef SQLITE_OMIT_SUBQUERY /* ** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo() ** interface. ** ** For each FROM-clause subquery, add Column.zType and Column.zColl ** information to the Table structure that represents the result set ** of that subquery. ** ** The Table structure that represents the result set was constructed ** by selectExpander() but the type and collation information was omitted ** at that point because identifiers had not yet been resolved. This ** routine is called after identifier resolution. */ static void selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){ Parse *pParse; int i; SrcList *pTabList; struct SrcList_item *pFrom; assert( p->selFlags & SF_Resolved ); assert( (p->selFlags & SF_HasTypeInfo)==0 ); p->selFlags |= SF_HasTypeInfo; pParse = pWalker->pParse; pTabList = p->pSrc; for(i=0, pFrom=pTabList->a; inSrc; i++, pFrom++){ Table *pTab = pFrom->pTab; assert( pTab!=0 ); if( (pTab->tabFlags & TF_Ephemeral)!=0 ){ /* A sub-query in the FROM clause of a SELECT */ Select *pSel = pFrom->pSelect; if( pSel ){ while( pSel->pPrior ) pSel = pSel->pPrior; sqlite3SelectAddColumnTypeAndCollation(pParse, pTab, pSel); } } } } #endif /* ** This routine adds datatype and collating sequence information to ** the Table structures of all FROM-clause subqueries in a ** SELECT statement. ** ** Use this routine after name resolution. */ static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){ #ifndef SQLITE_OMIT_SUBQUERY Walker w; memset(&w, 0, sizeof(w)); w.xSelectCallback2 = selectAddSubqueryTypeInfo; w.xExprCallback = sqlite3ExprWalkNoop; w.pParse = pParse; sqlite3WalkSelect(&w, pSelect); #endif } /* ** This routine sets up a SELECT statement for processing. The ** following is accomplished: ** ** * VDBE Cursor numbers are assigned to all FROM-clause terms. ** * Ephemeral Table objects are created for all FROM-clause subqueries. ** * ON and USING clauses are shifted into WHERE statements ** * Wildcards "*" and "TABLE.*" in result sets are expanded. ** * Identifiers in expression are matched to tables. ** ** This routine acts recursively on all subqueries within the SELECT. */ void sqlite3SelectPrep( Parse *pParse, /* The parser context */ Select *p, /* The SELECT statement being coded. */ NameContext *pOuterNC /* Name context for container */ ){ sqlite3 *db; if( NEVER(p==0) ) return; db = pParse->db; if( db->mallocFailed ) return; if( p->selFlags & SF_HasTypeInfo ) return; sqlite3SelectExpand(pParse, p); if( pParse->nErr || db->mallocFailed ) return; sqlite3ResolveSelectNames(pParse, p, pOuterNC); if( pParse->nErr || db->mallocFailed ) return; sqlite3SelectAddTypeInfo(pParse, p); } /* ** Reset the aggregate accumulator. ** ** The aggregate accumulator is a set of memory cells that hold ** intermediate results while calculating an aggregate. This ** routine generates code that stores NULLs in all of those memory ** cells. */ static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){ Vdbe *v = pParse->pVdbe; int i; struct AggInfo_func *pFunc; int nReg = pAggInfo->nFunc + pAggInfo->nColumn; if( nReg==0 ) return; #ifdef SQLITE_DEBUG /* Verify that all AggInfo registers are within the range specified by ** AggInfo.mnReg..AggInfo.mxReg */ assert( nReg==pAggInfo->mxReg-pAggInfo->mnReg+1 ); for(i=0; inColumn; i++){ assert( pAggInfo->aCol[i].iMem>=pAggInfo->mnReg && pAggInfo->aCol[i].iMem<=pAggInfo->mxReg ); } for(i=0; inFunc; i++){ assert( pAggInfo->aFunc[i].iMem>=pAggInfo->mnReg && pAggInfo->aFunc[i].iMem<=pAggInfo->mxReg ); } #endif sqlite3VdbeAddOp3(v, OP_Null, 0, pAggInfo->mnReg, pAggInfo->mxReg); for(pFunc=pAggInfo->aFunc, i=0; inFunc; i++, pFunc++){ if( pFunc->iDistinct>=0 ){ Expr *pE = pFunc->pExpr; assert( !ExprHasProperty(pE, EP_xIsSelect) ); if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){ sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one " "argument"); pFunc->iDistinct = -1; }else{ KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList, 0, 0); sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0, (char*)pKeyInfo, P4_KEYINFO); } } } } /* ** Invoke the OP_AggFinalize opcode for every aggregate function ** in the AggInfo structure. */ static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){ Vdbe *v = pParse->pVdbe; int i; struct AggInfo_func *pF; for(i=0, pF=pAggInfo->aFunc; inFunc; i++, pF++){ ExprList *pList = pF->pExpr->x.pList; assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) ); sqlite3VdbeAddOp4(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0, 0, (void*)pF->pFunc, P4_FUNCDEF); } } /* ** Update the accumulator memory cells for an aggregate based on ** the current cursor position. */ static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){ Vdbe *v = pParse->pVdbe; int i; int regHit = 0; int addrHitTest = 0; struct AggInfo_func *pF; struct AggInfo_col *pC; pAggInfo->directMode = 1; for(i=0, pF=pAggInfo->aFunc; inFunc; i++, pF++){ int nArg; int addrNext = 0; int regAgg; ExprList *pList = pF->pExpr->x.pList; assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) ); if( pList ){ nArg = pList->nExpr; regAgg = sqlite3GetTempRange(pParse, nArg); sqlite3ExprCodeExprList(pParse, pList, regAgg, 0, SQLITE_ECEL_DUP); }else{ nArg = 0; regAgg = 0; } if( pF->iDistinct>=0 ){ addrNext = sqlite3VdbeMakeLabel(v); testcase( nArg==0 ); /* Error condition */ testcase( nArg>1 ); /* Also an error */ codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg); } if( pF->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){ CollSeq *pColl = 0; struct ExprList_item *pItem; int j; assert( pList!=0 ); /* pList!=0 if pF->pFunc has NEEDCOLL */ for(j=0, pItem=pList->a; !pColl && jpExpr); } if( !pColl ){ pColl = pParse->db->pDfltColl; } if( regHit==0 && pAggInfo->nAccumulator ) regHit = ++pParse->nMem; sqlite3VdbeAddOp4(v, OP_CollSeq, regHit, 0, 0, (char *)pColl, P4_COLLSEQ); } sqlite3VdbeAddOp4(v, OP_AggStep0, 0, regAgg, pF->iMem, (void*)pF->pFunc, P4_FUNCDEF); sqlite3VdbeChangeP5(v, (u8)nArg); sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg); sqlite3ReleaseTempRange(pParse, regAgg, nArg); if( addrNext ){ sqlite3VdbeResolveLabel(v, addrNext); sqlite3ExprCacheClear(pParse); } } /* Before populating the accumulator registers, clear the column cache. ** Otherwise, if any of the required column values are already present ** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value ** to pC->iMem. But by the time the value is used, the original register ** may have been used, invalidating the underlying buffer holding the ** text or blob value. See ticket [883034dcb5]. ** ** Another solution would be to change the OP_SCopy used to copy cached ** values to an OP_Copy. */ if( regHit ){ addrHitTest = sqlite3VdbeAddOp1(v, OP_If, regHit); VdbeCoverage(v); } sqlite3ExprCacheClear(pParse); for(i=0, pC=pAggInfo->aCol; inAccumulator; i++, pC++){ sqlite3ExprCode(pParse, pC->pExpr, pC->iMem); } pAggInfo->directMode = 0; sqlite3ExprCacheClear(pParse); if( addrHitTest ){ sqlite3VdbeJumpHere(v, addrHitTest); } } /* ** Add a single OP_Explain instruction to the VDBE to explain a simple ** count(*) query ("SELECT count(*) FROM pTab"). */ #ifndef SQLITE_OMIT_EXPLAIN static void explainSimpleCount( Parse *pParse, /* Parse context */ Table *pTab, /* Table being queried */ Index *pIdx /* Index used to optimize scan, or NULL */ ){ if( pParse->explain==2 ){ int bCover = (pIdx!=0 && (HasRowid(pTab) || !IsPrimaryKeyIndex(pIdx))); char *zEqp = sqlite3MPrintf(pParse->db, "SCAN TABLE %s%s%s", pTab->zName, bCover ? " USING COVERING INDEX " : "", bCover ? pIdx->zName : "" ); sqlite3VdbeAddOp4( pParse->pVdbe, OP_Explain, pParse->iSelectId, 0, 0, zEqp, P4_DYNAMIC ); } } #else # define explainSimpleCount(a,b,c) #endif /* ** Generate code for the SELECT statement given in the p argument. ** ** The results are returned according to the SelectDest structure. ** See comments in sqliteInt.h for further information. ** ** This routine returns the number of errors. If any errors are ** encountered, then an appropriate error message is left in ** pParse->zErrMsg. ** ** This routine does NOT free the Select structure passed in. The ** calling function needs to do that. */ int sqlite3Select( Parse *pParse, /* The parser context */ Select *p, /* The SELECT statement being coded. */ SelectDest *pDest /* What to do with the query results */ ){ int i, j; /* Loop counters */ WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */ Vdbe *v; /* The virtual machine under construction */ int isAgg; /* True for select lists like "count(*)" */ ExprList *pEList = 0; /* List of columns to extract. */ SrcList *pTabList; /* List of tables to select from */ Expr *pWhere; /* The WHERE clause. May be NULL */ ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */ Expr *pHaving; /* The HAVING clause. May be NULL */ int rc = 1; /* Value to return from this function */ DistinctCtx sDistinct; /* Info on how to code the DISTINCT keyword */ SortCtx sSort; /* Info on how to code the ORDER BY clause */ AggInfo sAggInfo; /* Information used by aggregate queries */ int iEnd; /* Address of the end of the query */ sqlite3 *db; /* The database connection */ #ifndef SQLITE_OMIT_EXPLAIN int iRestoreSelectId = pParse->iSelectId; pParse->iSelectId = pParse->iNextSelectId++; #endif db = pParse->db; if( p==0 || db->mallocFailed || pParse->nErr ){ return 1; } if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1; memset(&sAggInfo, 0, sizeof(sAggInfo)); #if SELECTTRACE_ENABLED pParse->nSelectIndent++; SELECTTRACE(1,pParse,p, ("begin processing:\n")); if( sqlite3SelectTrace & 0x100 ){ sqlite3TreeViewSelect(0, p, 0); } #endif assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistFifo ); assert( p->pOrderBy==0 || pDest->eDest!=SRT_Fifo ); assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistQueue ); assert( p->pOrderBy==0 || pDest->eDest!=SRT_Queue ); if( IgnorableOrderby(pDest) ){ assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union || pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard || pDest->eDest==SRT_Queue || pDest->eDest==SRT_DistFifo || pDest->eDest==SRT_DistQueue || pDest->eDest==SRT_Fifo); /* If ORDER BY makes no difference in the output then neither does ** DISTINCT so it can be removed too. */ sqlite3ExprListDelete(db, p->pOrderBy); p->pOrderBy = 0; p->selFlags &= ~SF_Distinct; } sqlite3SelectPrep(pParse, p, 0); memset(&sSort, 0, sizeof(sSort)); sSort.pOrderBy = p->pOrderBy; pTabList = p->pSrc; if( pParse->nErr || db->mallocFailed ){ goto select_end; } assert( p->pEList!=0 ); isAgg = (p->selFlags & SF_Aggregate)!=0; #if SELECTTRACE_ENABLED if( sqlite3SelectTrace & 0x100 ){ SELECTTRACE(0x100,pParse,p, ("after name resolution:\n")); sqlite3TreeViewSelect(0, p, 0); } #endif /* Try to flatten subqueries in the FROM clause up into the main query */ #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) for(i=0; !p->pPrior && inSrc; i++){ struct SrcList_item *pItem = &pTabList->a[i]; Select *pSub = pItem->pSelect; int isAggSub; Table *pTab = pItem->pTab; if( pSub==0 ) continue; /* Catch mismatch in the declared columns of a view and the number of ** columns in the SELECT on the RHS */ if( pTab->nCol!=pSub->pEList->nExpr ){ sqlite3ErrorMsg(pParse, "expected %d columns for '%s' but got %d", pTab->nCol, pTab->zName, pSub->pEList->nExpr); goto select_end; } isAggSub = (pSub->selFlags & SF_Aggregate)!=0; if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){ /* This subquery can be absorbed into its parent. */ if( isAggSub ){ isAgg = 1; p->selFlags |= SF_Aggregate; } i = -1; } pTabList = p->pSrc; if( db->mallocFailed ) goto select_end; if( !IgnorableOrderby(pDest) ){ sSort.pOrderBy = p->pOrderBy; } } #endif /* Get a pointer the VDBE under construction, allocating a new VDBE if one ** does not already exist */ v = sqlite3GetVdbe(pParse); if( v==0 ) goto select_end; #ifndef SQLITE_OMIT_COMPOUND_SELECT /* Handle compound SELECT statements using the separate multiSelect() ** procedure. */ if( p->pPrior ){ rc = multiSelect(pParse, p, pDest); explainSetInteger(pParse->iSelectId, iRestoreSelectId); #if SELECTTRACE_ENABLED SELECTTRACE(1,pParse,p,("end compound-select processing\n")); pParse->nSelectIndent--; #endif return rc; } #endif /* Generate code for all sub-queries in the FROM clause */ #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) for(i=0; inSrc; i++){ struct SrcList_item *pItem = &pTabList->a[i]; SelectDest dest; Select *pSub = pItem->pSelect; if( pSub==0 ) continue; /* Sometimes the code for a subquery will be generated more than ** once, if the subquery is part of the WHERE clause in a LEFT JOIN, ** for example. In that case, do not regenerate the code to manifest ** a view or the co-routine to implement a view. The first instance ** is sufficient, though the subroutine to manifest the view does need ** to be invoked again. */ if( pItem->addrFillSub ){ if( pItem->fg.viaCoroutine==0 ){ sqlite3VdbeAddOp2(v, OP_Gosub, pItem->regReturn, pItem->addrFillSub); } continue; } /* Increment Parse.nHeight by the height of the largest expression ** tree referred to by this, the parent select. The child select ** may contain expression trees of at most ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit ** more conservative than necessary, but much easier than enforcing ** an exact limit. */ pParse->nHeight += sqlite3SelectExprHeight(p); /* Make copies of constant WHERE-clause terms in the outer query down ** inside the subquery. This can help the subquery to run more efficiently. */ if( (pItem->fg.jointype & JT_OUTER)==0 && pushDownWhereTerms(db, pSub, p->pWhere, pItem->iCursor) ){ #if SELECTTRACE_ENABLED if( sqlite3SelectTrace & 0x100 ){ SELECTTRACE(0x100,pParse,p,("After WHERE-clause push-down:\n")); sqlite3TreeViewSelect(0, p, 0); } #endif } /* Generate code to implement the subquery ** ** The subquery is implemented as a co-routine if all of these are true: ** (1) The subquery is guaranteed to be the outer loop (so that it ** does not need to be computed more than once) ** (2) The ALL keyword after SELECT is omitted. (Applications are ** allowed to say "SELECT ALL" instead of just "SELECT" to disable ** the use of co-routines.) ** (3) Co-routines are not disabled using sqlite3_test_control() ** with SQLITE_TESTCTRL_OPTIMIZATIONS. ** ** TODO: Are there other reasons beside (1) to use a co-routine ** implementation? */ if( i==0 && (pTabList->nSrc==1 || (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0) /* (1) */ && (p->selFlags & SF_All)==0 /* (2) */ && OptimizationEnabled(db, SQLITE_SubqCoroutine) /* (3) */ ){ /* Implement a co-routine that will return a single row of the result ** set on each invocation. */ int addrTop = sqlite3VdbeCurrentAddr(v)+1; pItem->regReturn = ++pParse->nMem; sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop); VdbeComment((v, "%s", pItem->pTab->zName)); pItem->addrFillSub = addrTop; sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn); explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId); sqlite3Select(pParse, pSub, &dest); pItem->pTab->nRowLogEst = pSub->nSelectRow; pItem->fg.viaCoroutine = 1; pItem->regResult = dest.iSdst; sqlite3VdbeEndCoroutine(v, pItem->regReturn); sqlite3VdbeJumpHere(v, addrTop-1); sqlite3ClearTempRegCache(pParse); }else{ /* Generate a subroutine that will fill an ephemeral table with ** the content of this subquery. pItem->addrFillSub will point ** to the address of the generated subroutine. pItem->regReturn ** is a register allocated to hold the subroutine return address */ int topAddr; int onceAddr = 0; int retAddr; assert( pItem->addrFillSub==0 ); pItem->regReturn = ++pParse->nMem; topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn); pItem->addrFillSub = topAddr+1; if( pItem->fg.isCorrelated==0 ){ /* If the subquery is not correlated and if we are not inside of ** a trigger, then we only need to compute the value of the subquery ** once. */ onceAddr = sqlite3CodeOnce(pParse); VdbeCoverage(v); VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName)); }else{ VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName)); } sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor); explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId); sqlite3Select(pParse, pSub, &dest); pItem->pTab->nRowLogEst = pSub->nSelectRow; if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr); retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn); VdbeComment((v, "end %s", pItem->pTab->zName)); sqlite3VdbeChangeP1(v, topAddr, retAddr); sqlite3ClearTempRegCache(pParse); } if( db->mallocFailed ) goto select_end; pParse->nHeight -= sqlite3SelectExprHeight(p); } #endif /* Various elements of the SELECT copied into local variables for ** convenience */ pEList = p->pEList; pWhere = p->pWhere; pGroupBy = p->pGroupBy; pHaving = p->pHaving; sDistinct.isTnct = (p->selFlags & SF_Distinct)!=0; #if SELECTTRACE_ENABLED if( sqlite3SelectTrace & 0x400 ){ SELECTTRACE(0x400,pParse,p,("After all FROM-clause analysis:\n")); sqlite3TreeViewSelect(0, p, 0); } #endif /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and ** if the select-list is the same as the ORDER BY list, then this query ** can be rewritten as a GROUP BY. In other words, this: ** ** SELECT DISTINCT xyz FROM ... ORDER BY xyz ** ** is transformed to: ** ** SELECT xyz FROM ... GROUP BY xyz ORDER BY xyz ** ** The second form is preferred as a single index (or temp-table) may be ** used for both the ORDER BY and DISTINCT processing. As originally ** written the query must use a temp-table for at least one of the ORDER ** BY and DISTINCT, and an index or separate temp-table for the other. */ if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct && sqlite3ExprListCompare(sSort.pOrderBy, pEList, -1)==0 ){ p->selFlags &= ~SF_Distinct; pGroupBy = p->pGroupBy = sqlite3ExprListDup(db, pEList, 0); /* Notice that even thought SF_Distinct has been cleared from p->selFlags, ** the sDistinct.isTnct is still set. Hence, isTnct represents the ** original setting of the SF_Distinct flag, not the current setting */ assert( sDistinct.isTnct ); #if SELECTTRACE_ENABLED if( sqlite3SelectTrace & 0x400 ){ SELECTTRACE(0x400,pParse,p,("Transform DISTINCT into GROUP BY:\n")); sqlite3TreeViewSelect(0, p, 0); } #endif } /* If there is an ORDER BY clause, then create an ephemeral index to ** do the sorting. But this sorting ephemeral index might end up ** being unused if the data can be extracted in pre-sorted order. ** If that is the case, then the OP_OpenEphemeral instruction will be ** changed to an OP_Noop once we figure out that the sorting index is ** not needed. The sSort.addrSortIndex variable is used to facilitate ** that change. */ if( sSort.pOrderBy ){ KeyInfo *pKeyInfo; pKeyInfo = keyInfoFromExprList(pParse, sSort.pOrderBy, 0, pEList->nExpr); sSort.iECursor = pParse->nTab++; sSort.addrSortIndex = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, sSort.iECursor, sSort.pOrderBy->nExpr+1+pEList->nExpr, 0, (char*)pKeyInfo, P4_KEYINFO ); }else{ sSort.addrSortIndex = -1; } /* If the output is destined for a temporary table, open that table. */ if( pDest->eDest==SRT_EphemTab ){ sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iSDParm, pEList->nExpr); } /* Set the limiter. */ iEnd = sqlite3VdbeMakeLabel(v); p->nSelectRow = 320; /* 4 billion rows */ computeLimitRegisters(pParse, p, iEnd); if( p->iLimit==0 && sSort.addrSortIndex>=0 ){ sqlite3VdbeChangeOpcode(v, sSort.addrSortIndex, OP_SorterOpen); sSort.sortFlags |= SORTFLAG_UseSorter; } /* Open an ephemeral index to use for the distinct set. */ if( p->selFlags & SF_Distinct ){ sDistinct.tabTnct = pParse->nTab++; sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, sDistinct.tabTnct, 0, 0, (char*)keyInfoFromExprList(pParse, p->pEList,0,0), P4_KEYINFO); sqlite3VdbeChangeP5(v, BTREE_UNORDERED); sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED; }else{ sDistinct.eTnctType = WHERE_DISTINCT_NOOP; } if( !isAgg && pGroupBy==0 ){ /* No aggregate functions and no GROUP BY clause */ u16 wctrlFlags = (sDistinct.isTnct ? WHERE_WANT_DISTINCT : 0); assert( WHERE_USE_LIMIT==SF_FixedLimit ); wctrlFlags |= p->selFlags & SF_FixedLimit; /* Begin the database scan. */ pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, sSort.pOrderBy, p->pEList, wctrlFlags, p->nSelectRow); if( pWInfo==0 ) goto select_end; if( sqlite3WhereOutputRowCount(pWInfo) < p->nSelectRow ){ p->nSelectRow = sqlite3WhereOutputRowCount(pWInfo); } if( sDistinct.isTnct && sqlite3WhereIsDistinct(pWInfo) ){ sDistinct.eTnctType = sqlite3WhereIsDistinct(pWInfo); } if( sSort.pOrderBy ){ sSort.nOBSat = sqlite3WhereIsOrdered(pWInfo); sSort.bOrderedInnerLoop = sqlite3WhereOrderedInnerLoop(pWInfo); if( sSort.nOBSat==sSort.pOrderBy->nExpr ){ sSort.pOrderBy = 0; } } /* If sorting index that was created by a prior OP_OpenEphemeral ** instruction ended up not being needed, then change the OP_OpenEphemeral ** into an OP_Noop. */ if( sSort.addrSortIndex>=0 && sSort.pOrderBy==0 ){ sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex); } /* Use the standard inner loop. */ selectInnerLoop(pParse, p, pEList, -1, &sSort, &sDistinct, pDest, sqlite3WhereContinueLabel(pWInfo), sqlite3WhereBreakLabel(pWInfo)); /* End the database scan loop. */ sqlite3WhereEnd(pWInfo); }else{ /* This case when there exist aggregate functions or a GROUP BY clause ** or both */ NameContext sNC; /* Name context for processing aggregate information */ int iAMem; /* First Mem address for storing current GROUP BY */ int iBMem; /* First Mem address for previous GROUP BY */ int iUseFlag; /* Mem address holding flag indicating that at least ** one row of the input to the aggregator has been ** processed */ int iAbortFlag; /* Mem address which causes query abort if positive */ int groupBySort; /* Rows come from source in GROUP BY order */ int addrEnd; /* End of processing for this SELECT */ int sortPTab = 0; /* Pseudotable used to decode sorting results */ int sortOut = 0; /* Output register from the sorter */ int orderByGrp = 0; /* True if the GROUP BY and ORDER BY are the same */ /* Remove any and all aliases between the result set and the ** GROUP BY clause. */ if( pGroupBy ){ int k; /* Loop counter */ struct ExprList_item *pItem; /* For looping over expression in a list */ for(k=p->pEList->nExpr, pItem=p->pEList->a; k>0; k--, pItem++){ pItem->u.x.iAlias = 0; } for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){ pItem->u.x.iAlias = 0; } assert( 66==sqlite3LogEst(100) ); if( p->nSelectRow>66 ) p->nSelectRow = 66; }else{ assert( 0==sqlite3LogEst(1) ); p->nSelectRow = 0; } /* If there is both a GROUP BY and an ORDER BY clause and they are ** identical, then it may be possible to disable the ORDER BY clause ** on the grounds that the GROUP BY will cause elements to come out ** in the correct order. It also may not - the GROUP BY might use a ** database index that causes rows to be grouped together as required ** but not actually sorted. Either way, record the fact that the ** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp ** variable. */ if( sqlite3ExprListCompare(pGroupBy, sSort.pOrderBy, -1)==0 ){ orderByGrp = 1; } /* Create a label to jump to when we want to abort the query */ addrEnd = sqlite3VdbeMakeLabel(v); /* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the ** SELECT statement. */ memset(&sNC, 0, sizeof(sNC)); sNC.pParse = pParse; sNC.pSrcList = pTabList; sNC.pAggInfo = &sAggInfo; sAggInfo.mnReg = pParse->nMem+1; sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr : 0; sAggInfo.pGroupBy = pGroupBy; sqlite3ExprAnalyzeAggList(&sNC, pEList); sqlite3ExprAnalyzeAggList(&sNC, sSort.pOrderBy); if( pHaving ){ sqlite3ExprAnalyzeAggregates(&sNC, pHaving); } sAggInfo.nAccumulator = sAggInfo.nColumn; for(i=0; ix.pList); sNC.ncFlags &= ~NC_InAggFunc; } sAggInfo.mxReg = pParse->nMem; if( db->mallocFailed ) goto select_end; /* Processing for aggregates with GROUP BY is very different and ** much more complex than aggregates without a GROUP BY. */ if( pGroupBy ){ KeyInfo *pKeyInfo; /* Keying information for the group by clause */ int addr1; /* A-vs-B comparision jump */ int addrOutputRow; /* Start of subroutine that outputs a result row */ int regOutputRow; /* Return address register for output subroutine */ int addrSetAbort; /* Set the abort flag and return */ int addrTopOfLoop; /* Top of the input loop */ int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */ int addrReset; /* Subroutine for resetting the accumulator */ int regReset; /* Return address register for reset subroutine */ /* If there is a GROUP BY clause we might need a sorting index to ** implement it. Allocate that sorting index now. If it turns out ** that we do not need it after all, the OP_SorterOpen instruction ** will be converted into a Noop. */ sAggInfo.sortingIdx = pParse->nTab++; pKeyInfo = keyInfoFromExprList(pParse, pGroupBy, 0, sAggInfo.nColumn); addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, sAggInfo.sortingIdx, sAggInfo.nSortingColumn, 0, (char*)pKeyInfo, P4_KEYINFO); /* Initialize memory locations used by GROUP BY aggregate processing */ iUseFlag = ++pParse->nMem; iAbortFlag = ++pParse->nMem; regOutputRow = ++pParse->nMem; addrOutputRow = sqlite3VdbeMakeLabel(v); regReset = ++pParse->nMem; addrReset = sqlite3VdbeMakeLabel(v); iAMem = pParse->nMem + 1; pParse->nMem += pGroupBy->nExpr; iBMem = pParse->nMem + 1; pParse->nMem += pGroupBy->nExpr; sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag); VdbeComment((v, "clear abort flag")); sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag); VdbeComment((v, "indicate accumulator empty")); sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1); /* Begin a loop that will extract all source rows in GROUP BY order. ** This might involve two separate loops with an OP_Sort in between, or ** it might be a single loop that uses an index to extract information ** in the right order to begin with. */ sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, 0, WHERE_GROUPBY | (orderByGrp ? WHERE_SORTBYGROUP : 0), 0 ); if( pWInfo==0 ) goto select_end; if( sqlite3WhereIsOrdered(pWInfo)==pGroupBy->nExpr ){ /* The optimizer is able to deliver rows in group by order so ** we do not have to sort. The OP_OpenEphemeral table will be ** cancelled later because we still need to use the pKeyInfo */ groupBySort = 0; }else{ /* Rows are coming out in undetermined order. We have to push ** each row into a sorting index, terminate the first loop, ** then loop over the sorting index in order to get the output ** in sorted order */ int regBase; int regRecord; int nCol; int nGroupBy; explainTempTable(pParse, (sDistinct.isTnct && (p->selFlags&SF_Distinct)==0) ? "DISTINCT" : "GROUP BY"); groupBySort = 1; nGroupBy = pGroupBy->nExpr; nCol = nGroupBy; j = nGroupBy; for(i=0; i=j ){ nCol++; j++; } } regBase = sqlite3GetTempRange(pParse, nCol); sqlite3ExprCacheClear(pParse); sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0, 0); j = nGroupBy; for(i=0; iiSorterColumn>=j ){ int r1 = j + regBase; sqlite3ExprCodeGetColumnToReg(pParse, pCol->pTab, pCol->iColumn, pCol->iTable, r1); j++; } } regRecord = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord); sqlite3VdbeAddOp2(v, OP_SorterInsert, sAggInfo.sortingIdx, regRecord); sqlite3ReleaseTempReg(pParse, regRecord); sqlite3ReleaseTempRange(pParse, regBase, nCol); sqlite3WhereEnd(pWInfo); sAggInfo.sortingIdxPTab = sortPTab = pParse->nTab++; sortOut = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol); sqlite3VdbeAddOp2(v, OP_SorterSort, sAggInfo.sortingIdx, addrEnd); VdbeComment((v, "GROUP BY sort")); VdbeCoverage(v); sAggInfo.useSortingIdx = 1; sqlite3ExprCacheClear(pParse); } /* If the index or temporary table used by the GROUP BY sort ** will naturally deliver rows in the order required by the ORDER BY ** clause, cancel the ephemeral table open coded earlier. ** ** This is an optimization - the correct answer should result regardless. ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER to ** disable this optimization for testing purposes. */ if( orderByGrp && OptimizationEnabled(db, SQLITE_GroupByOrder) && (groupBySort || sqlite3WhereIsSorted(pWInfo)) ){ sSort.pOrderBy = 0; sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex); } /* Evaluate the current GROUP BY terms and store in b0, b1, b2... ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth) ** Then compare the current GROUP BY terms against the GROUP BY terms ** from the previous row currently stored in a0, a1, a2... */ addrTopOfLoop = sqlite3VdbeCurrentAddr(v); sqlite3ExprCacheClear(pParse); if( groupBySort ){ sqlite3VdbeAddOp3(v, OP_SorterData, sAggInfo.sortingIdx, sortOut, sortPTab); } for(j=0; jnExpr; j++){ if( groupBySort ){ sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j); }else{ sAggInfo.directMode = 1; sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j); } } sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr, (char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO); addr1 = sqlite3VdbeCurrentAddr(v); sqlite3VdbeAddOp3(v, OP_Jump, addr1+1, 0, addr1+1); VdbeCoverage(v); /* Generate code that runs whenever the GROUP BY changes. ** Changes in the GROUP BY are detected by the previous code ** block. If there were no changes, this block is skipped. ** ** This code copies current group by terms in b0,b1,b2,... ** over to a0,a1,a2. It then calls the output subroutine ** and resets the aggregate accumulator registers in preparation ** for the next GROUP BY batch. */ sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr); sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow); VdbeComment((v, "output one row")); sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd); VdbeCoverage(v); VdbeComment((v, "check abort flag")); sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); VdbeComment((v, "reset accumulator")); /* Update the aggregate accumulators based on the content of ** the current row */ sqlite3VdbeJumpHere(v, addr1); updateAccumulator(pParse, &sAggInfo); sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag); VdbeComment((v, "indicate data in accumulator")); /* End of the loop */ if( groupBySort ){ sqlite3VdbeAddOp2(v, OP_SorterNext, sAggInfo.sortingIdx, addrTopOfLoop); VdbeCoverage(v); }else{ sqlite3WhereEnd(pWInfo); sqlite3VdbeChangeToNoop(v, addrSortingIdx); } /* Output the final row of result */ sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow); VdbeComment((v, "output final row")); /* Jump over the subroutines */ sqlite3VdbeGoto(v, addrEnd); /* Generate a subroutine that outputs a single row of the result ** set. This subroutine first looks at the iUseFlag. If iUseFlag ** is less than or equal to zero, the subroutine is a no-op. If ** the processing calls for the query to abort, this subroutine ** increments the iAbortFlag memory location before returning in ** order to signal the caller to abort. */ addrSetAbort = sqlite3VdbeCurrentAddr(v); sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag); VdbeComment((v, "set abort flag")); sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); sqlite3VdbeResolveLabel(v, addrOutputRow); addrOutputRow = sqlite3VdbeCurrentAddr(v); sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2); VdbeCoverage(v); VdbeComment((v, "Groupby result generator entry point")); sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); finalizeAggFunctions(pParse, &sAggInfo); sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL); selectInnerLoop(pParse, p, p->pEList, -1, &sSort, &sDistinct, pDest, addrOutputRow+1, addrSetAbort); sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); VdbeComment((v, "end groupby result generator")); /* Generate a subroutine that will reset the group-by accumulator */ sqlite3VdbeResolveLabel(v, addrReset); resetAccumulator(pParse, &sAggInfo); sqlite3VdbeAddOp1(v, OP_Return, regReset); } /* endif pGroupBy. Begin aggregate queries without GROUP BY: */ else { ExprList *pDel = 0; #ifndef SQLITE_OMIT_BTREECOUNT Table *pTab; if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){ /* If isSimpleCount() returns a pointer to a Table structure, then ** the SQL statement is of the form: ** ** SELECT count(*) FROM ** ** where the Table structure returned represents table . ** ** This statement is so common that it is optimized specially. The ** OP_Count instruction is executed either on the intkey table that ** contains the data for table or on one of its indexes. It ** is better to execute the op on an index, as indexes are almost ** always spread across less pages than their corresponding tables. */ const int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema); const int iCsr = pParse->nTab++; /* Cursor to scan b-tree */ Index *pIdx; /* Iterator variable */ KeyInfo *pKeyInfo = 0; /* Keyinfo for scanned index */ Index *pBest = 0; /* Best index found so far */ int iRoot = pTab->tnum; /* Root page of scanned b-tree */ sqlite3CodeVerifySchema(pParse, iDb); sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName); /* Search for the index that has the lowest scan cost. ** ** (2011-04-15) Do not do a full scan of an unordered index. ** ** (2013-10-03) Do not count the entries in a partial index. ** ** In practice the KeyInfo structure will not be used. It is only ** passed to keep OP_OpenRead happy. */ if( !HasRowid(pTab) ) pBest = sqlite3PrimaryKeyIndex(pTab); for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ if( pIdx->bUnordered==0 && pIdx->szIdxRowszTabRow && pIdx->pPartIdxWhere==0 && (!pBest || pIdx->szIdxRowszIdxRow) ){ pBest = pIdx; } } if( pBest ){ iRoot = pBest->tnum; pKeyInfo = sqlite3KeyInfoOfIndex(pParse, pBest); } /* Open a read-only cursor, execute the OP_Count, close the cursor. */ sqlite3VdbeAddOp4Int(v, OP_OpenRead, iCsr, iRoot, iDb, 1); if( pKeyInfo ){ sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO); } sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem); sqlite3VdbeAddOp1(v, OP_Close, iCsr); explainSimpleCount(pParse, pTab, pBest); }else #endif /* SQLITE_OMIT_BTREECOUNT */ { /* Check if the query is of one of the following forms: ** ** SELECT min(x) FROM ... ** SELECT max(x) FROM ... ** ** If it is, then ask the code in where.c to attempt to sort results ** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause. ** If where.c is able to produce results sorted in this order, then ** add vdbe code to break out of the processing loop after the ** first iteration (since the first iteration of the loop is ** guaranteed to operate on the row with the minimum or maximum ** value of x, the only row required). ** ** A special flag must be passed to sqlite3WhereBegin() to slightly ** modify behavior as follows: ** ** + If the query is a "SELECT min(x)", then the loop coded by ** where.c should not iterate over any values with a NULL value ** for x. ** ** + The optimizer code in where.c (the thing that decides which ** index or indices to use) should place a different priority on ** satisfying the 'ORDER BY' clause than it does in other cases. ** Refer to code and comments in where.c for details. */ ExprList *pMinMax = 0; u8 flag = WHERE_ORDERBY_NORMAL; assert( p->pGroupBy==0 ); assert( flag==0 ); if( p->pHaving==0 ){ flag = minMaxQuery(&sAggInfo, &pMinMax); } assert( flag==0 || (pMinMax!=0 && pMinMax->nExpr==1) ); if( flag ){ pMinMax = sqlite3ExprListDup(db, pMinMax, 0); pDel = pMinMax; assert( db->mallocFailed || pMinMax!=0 ); if( !db->mallocFailed ){ pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0; pMinMax->a[0].pExpr->op = TK_COLUMN; } } /* This case runs if the aggregate has no GROUP BY clause. The ** processing is much simpler since there is only a single row ** of output. */ resetAccumulator(pParse, &sAggInfo); pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMax,0,flag,0); if( pWInfo==0 ){ sqlite3ExprListDelete(db, pDel); goto select_end; } updateAccumulator(pParse, &sAggInfo); assert( pMinMax==0 || pMinMax->nExpr==1 ); if( sqlite3WhereIsOrdered(pWInfo)>0 ){ sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo)); VdbeComment((v, "%s() by index", (flag==WHERE_ORDERBY_MIN?"min":"max"))); } sqlite3WhereEnd(pWInfo); finalizeAggFunctions(pParse, &sAggInfo); } sSort.pOrderBy = 0; sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL); selectInnerLoop(pParse, p, p->pEList, -1, 0, 0, pDest, addrEnd, addrEnd); sqlite3ExprListDelete(db, pDel); } sqlite3VdbeResolveLabel(v, addrEnd); } /* endif aggregate query */ if( sDistinct.eTnctType==WHERE_DISTINCT_UNORDERED ){ explainTempTable(pParse, "DISTINCT"); } /* If there is an ORDER BY clause, then we need to sort the results ** and send them to the callback one by one. */ if( sSort.pOrderBy ){ explainTempTable(pParse, sSort.nOBSat>0 ? "RIGHT PART OF ORDER BY":"ORDER BY"); generateSortTail(pParse, p, &sSort, pEList->nExpr, pDest); } /* Jump here to skip this query */ sqlite3VdbeResolveLabel(v, iEnd); /* The SELECT has been coded. If there is an error in the Parse structure, ** set the return code to 1. Otherwise 0. */ rc = (pParse->nErr>0); /* Control jumps to here if an error is encountered above, or upon ** successful coding of the SELECT. */ select_end: explainSetInteger(pParse->iSelectId, iRestoreSelectId); /* Identify column names if results of the SELECT are to be output. */ if( rc==SQLITE_OK && pDest->eDest==SRT_Output ){ generateColumnNames(pParse, pTabList, pEList); } sqlite3DbFree(db, sAggInfo.aCol); sqlite3DbFree(db, sAggInfo.aFunc); #if SELECTTRACE_ENABLED SELECTTRACE(1,pParse,p,("end processing\n")); pParse->nSelectIndent--; #endif return rc; }