/* ** 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" /* ** Delete all the content of a Select structure but do not deallocate ** the select structure itself. */ static void clearSelect(sqlite3 *db, Select *p){ sqlite3ExprListDelete(db, p->pEList); sqlite3SrcListDelete(db, p->pSrc); sqlite3ExprDelete(db, p->pWhere); sqlite3ExprListDelete(db, p->pGroupBy); sqlite3ExprDelete(db, p->pHaving); sqlite3ExprListDelete(db, p->pOrderBy); sqlite3SelectDelete(db, p->pPrior); sqlite3ExprDelete(db, p->pLimit); sqlite3ExprDelete(db, p->pOffset); } /* ** Initialize a SelectDest structure. */ void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){ pDest->eDest = (u8)eDest; pDest->iParm = iParm; pDest->affinity = 0; pDest->iMem = 0; pDest->nMem = 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 */ int isDistinct, /* true if the DISTINCT keyword is present */ 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 = sqlite3DbMallocZero(db, sizeof(*pNew) ); assert( db->mallocFailed || !pOffset || pLimit ); /* OFFSET implies LIMIT */ if( pNew==0 ){ pNew = &standin; memset(pNew, 0, sizeof(*pNew)); } if( pEList==0 ){ pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0)); } pNew->pEList = pEList; pNew->pSrc = pSrc; pNew->pWhere = pWhere; pNew->pGroupBy = pGroupBy; pNew->pHaving = pHaving; pNew->pOrderBy = pOrderBy; pNew->selFlags = isDistinct ? SF_Distinct : 0; pNew->op = TK_SELECT; pNew->pLimit = pLimit; pNew->pOffset = pOffset; assert( pOffset==0 || pLimit!=0 ); pNew->addrOpenEphm[0] = -1; pNew->addrOpenEphm[1] = -1; pNew->addrOpenEphm[2] = -1; if( db->mallocFailed ) { clearSelect(db, pNew); if( pNew!=&standin ) sqlite3DbFree(db, pNew); pNew = 0; } return pNew; } /* ** Delete the given Select structure and all of its substructures. */ void sqlite3SelectDelete(sqlite3 *db, Select *p){ if( p ){ clearSelect(db, p); sqlite3DbFree(db, p); } } /* ** Given 1 to 3 identifiers preceeding 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( !ExprHasAnyProperty(pEq, EP_TokenOnly|EP_Reduced) ); ExprSetIrreducible(pEq); 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( !ExprHasAnyProperty(p, EP_TokenOnly|EP_Reduced) ); ExprSetIrreducible(p); p->iRightJoinTable = (i16)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->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->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; } /* ** Insert code into "v" that will push the record on the top of the ** stack into the sorter. */ static void pushOntoSorter( Parse *pParse, /* Parser context */ ExprList *pOrderBy, /* The ORDER BY clause */ Select *pSelect, /* The whole SELECT statement */ int regData /* Register holding data to be sorted */ ){ Vdbe *v = pParse->pVdbe; int nExpr = pOrderBy->nExpr; int regBase = sqlite3GetTempRange(pParse, nExpr+2); int regRecord = sqlite3GetTempReg(pParse); sqlite3ExprCacheClear(pParse); sqlite3ExprCodeExprList(pParse, pOrderBy, regBase, 0); sqlite3VdbeAddOp2(v, OP_Sequence, pOrderBy->iECursor, regBase+nExpr); sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+1, 1); sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nExpr + 2, regRecord); sqlite3VdbeAddOp2(v, OP_IdxInsert, pOrderBy->iECursor, regRecord); sqlite3ReleaseTempReg(pParse, regRecord); sqlite3ReleaseTempRange(pParse, regBase, nExpr+2); if( pSelect->iLimit ){ int addr1, addr2; int iLimit; if( pSelect->iOffset ){ iLimit = pSelect->iOffset+1; }else{ iLimit = pSelect->iLimit; } addr1 = sqlite3VdbeAddOp1(v, OP_IfZero, iLimit); sqlite3VdbeAddOp2(v, OP_AddImm, iLimit, -1); addr2 = sqlite3VdbeAddOp0(v, OP_Goto); sqlite3VdbeJumpHere(v, addr1); sqlite3VdbeAddOp1(v, OP_Last, pOrderBy->iECursor); sqlite3VdbeAddOp1(v, OP_Delete, pOrderBy->iECursor); sqlite3VdbeJumpHere(v, addr2); } } /* ** Add code to implement the OFFSET */ static void codeOffset( Vdbe *v, /* Generate code into this VM */ Select *p, /* The SELECT statement being coded */ int iContinue /* Jump here to skip the current record */ ){ if( p->iOffset && iContinue!=0 ){ int addr; sqlite3VdbeAddOp2(v, OP_AddImm, p->iOffset, -1); addr = sqlite3VdbeAddOp1(v, OP_IfNeg, p->iOffset); sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue); VdbeComment((v, "skip OFFSET records")); sqlite3VdbeJumpHere(v, addr); } } /* ** 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); sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1); sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1); sqlite3ReleaseTempReg(pParse, r1); } #ifndef SQLITE_OMIT_SUBQUERY /* ** Generate an error message when a SELECT is used within a subexpression ** (example: "a IN (SELECT * FROM table)") but it has more than 1 result ** column. We do this in a subroutine because the error used to occur ** in multiple places. (The error only occurs in one place now, but we ** retain the subroutine to minimize code disruption.) */ static int checkForMultiColumnSelectError( Parse *pParse, /* Parse context. */ SelectDest *pDest, /* Destination of SELECT results */ int nExpr /* Number of result columns returned by SELECT */ ){ int eDest = pDest->eDest; if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){ sqlite3ErrorMsg(pParse, "only a single result allowed for " "a SELECT that is part of an expression"); return 1; }else{ return 0; } } #endif /* ** This routine generates the code for the inside of the inner loop ** of a SELECT. ** ** If srcTab and nColumn are both zero, then the pEList expressions ** are evaluated in order to get the data for this row. If nColumn>0 ** then data is pulled from srcTab and pEList is used only to get the ** datatypes 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 */ int nColumn, /* Number of columns in the source table */ ExprList *pOrderBy, /* If not NULL, sort results using this key */ int distinct, /* If >=0, make sure results are 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->iParm; /* First argument to disposal method */ int nResultCol; /* Number of result columns */ assert( v ); if( NEVER(v==0) ) return; assert( pEList!=0 ); hasDistinct = distinct>=0; if( pOrderBy==0 && !hasDistinct ){ codeOffset(v, p, iContinue); } /* Pull the requested columns. */ if( nColumn>0 ){ nResultCol = nColumn; }else{ nResultCol = pEList->nExpr; } if( pDest->iMem==0 ){ pDest->iMem = pParse->nMem+1; pDest->nMem = nResultCol; pParse->nMem += nResultCol; }else{ assert( pDest->nMem==nResultCol ); } regResult = pDest->iMem; if( nColumn>0 ){ for(i=0; inExpr==nColumn ); codeDistinct(pParse, distinct, iContinue, nColumn, regResult); if( pOrderBy==0 ){ codeOffset(v, p, 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, nColumn, 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, nColumn); break; } #endif /* Store the result as data using a unique key. */ case SRT_Table: case SRT_EphemTab: { int r1 = sqlite3GetTempReg(pParse); testcase( eDest==SRT_Table ); testcase( eDest==SRT_EphemTab ); sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1); if( pOrderBy ){ pushOntoSorter(pParse, pOrderBy, p, r1); }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); } 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: { assert( nColumn==1 ); p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affinity); if( pOrderBy ){ /* 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, pOrderBy, p, regResult); }else{ int r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, 1, r1, &p->affinity, 1); sqlite3ExprCacheAffinityChange(pParse, regResult, 1); 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 and break out ** of the scan loop. */ case SRT_Mem: { assert( nColumn==1 ); if( pOrderBy ){ pushOntoSorter(pParse, pOrderBy, p, regResult); }else{ sqlite3ExprCodeMove(pParse, regResult, iParm, 1); /* The LIMIT clause will jump out of the loop for us */ } break; } #endif /* #ifndef SQLITE_OMIT_SUBQUERY */ /* Send the data to the callback function or to a subroutine. In the ** case of a subroutine, the subroutine itself is responsible for ** popping the data from the stack. */ case SRT_Coroutine: case SRT_Output: { testcase( eDest==SRT_Coroutine ); testcase( eDest==SRT_Output ); if( pOrderBy ){ int r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1); pushOntoSorter(pParse, pOrderBy, p, r1); sqlite3ReleaseTempReg(pParse, r1); }else if( eDest==SRT_Coroutine ){ sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm); }else{ sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn); sqlite3ExprCacheAffinityChange(pParse, regResult, nColumn); } break; } #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( pOrderBy==0 && p->iLimit ){ sqlite3VdbeAddOp3(v, OP_IfZero, p->iLimit, iBreak, -1); } } /* ** 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 obtain from malloc. The calling ** function is responsible for seeing that this structure is eventually ** freed. Add the KeyInfo structure to the P4 field of an opcode using ** P4_KEYINFO_HANDOFF is the usual way of dealing with this. */ static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){ sqlite3 *db = pParse->db; int nExpr; KeyInfo *pInfo; struct ExprList_item *pItem; int i; nExpr = pList->nExpr; pInfo = sqlite3DbMallocZero(db, sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) ); if( pInfo ){ pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr]; pInfo->nField = (u16)nExpr; pInfo->enc = ENC(db); pInfo->db = db; for(i=0, pItem=pList->a; ipExpr); if( !pColl ){ pColl = db->pDfltColl; } pInfo->aColl[i] = pColl; pInfo->aSortOrder[i] = pItem->sortOrder; } } return pInfo; } #ifndef SQLITE_OMIT_COMPOUND_SELECT /* ** 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; } #endif /* SQLITE_OMIT_COMPOUND_SELECT */ #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); } } /* ** 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); } } /* ** 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 explainComposite(v,w,x,y,z) # define explainSetInteger(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 */ Vdbe *v, /* Generate code into this VDBE */ int nColumn, /* Number of columns of data */ SelectDest *pDest /* Write the sorted results here */ ){ int addrBreak = sqlite3VdbeMakeLabel(v); /* Jump here to exit loop */ int addrContinue = sqlite3VdbeMakeLabel(v); /* Jump here for next cycle */ int addr; int iTab; int pseudoTab = 0; ExprList *pOrderBy = p->pOrderBy; int eDest = pDest->eDest; int iParm = pDest->iParm; int regRow; int regRowid; iTab = pOrderBy->iECursor; regRow = sqlite3GetTempReg(pParse); if( eDest==SRT_Output || eDest==SRT_Coroutine ){ pseudoTab = pParse->nTab++; sqlite3VdbeAddOp3(v, OP_OpenPseudo, pseudoTab, regRow, nColumn); regRowid = 0; }else{ regRowid = sqlite3GetTempReg(pParse); } addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); codeOffset(v, p, addrContinue); sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr + 1, regRow); switch( eDest ){ case SRT_Table: case SRT_EphemTab: { testcase( eDest==SRT_Table ); testcase( eDest==SRT_EphemTab ); sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid); sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid); sqlite3VdbeChangeP5(v, OPFLAG_APPEND); break; } #ifndef SQLITE_OMIT_SUBQUERY case SRT_Set: { assert( nColumn==1 ); sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, 1, regRowid, &p->affinity, 1); sqlite3ExprCacheAffinityChange(pParse, regRow, 1); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid); break; } case SRT_Mem: { assert( nColumn==1 ); sqlite3ExprCodeMove(pParse, regRow, iParm, 1); /* The LIMIT clause will terminate the loop for us */ break; } #endif default: { int i; assert( eDest==SRT_Output || eDest==SRT_Coroutine ); testcase( eDest==SRT_Output ); testcase( eDest==SRT_Coroutine ); for(i=0; iiMem+i ); sqlite3VdbeAddOp3(v, OP_Column, pseudoTab, i, pDest->iMem+i); if( i==0 ){ sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE); } } if( eDest==SRT_Output ){ sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iMem, nColumn); sqlite3ExprCacheAffinityChange(pParse, pDest->iMem, nColumn); }else{ sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm); } break; } } sqlite3ReleaseTempReg(pParse, regRow); sqlite3ReleaseTempReg(pParse, regRowid); /* The bottom of the loop */ sqlite3VdbeResolveLabel(v, addrContinue); sqlite3VdbeAddOp2(v, OP_Next, iTab, addr); sqlite3VdbeResolveLabel(v, addrBreak); if( eDest==SRT_Output || eDest==SRT_Coroutine ){ sqlite3VdbeAddOp2(v, OP_Close, pseudoTab, 0); } } /* ** Return a pointer to a string containing the 'declaration type' of the ** expression pExpr. The string may be treated as static by the caller. ** ** 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. */ static const char *columnType( NameContext *pNC, Expr *pExpr, const char **pzOriginDb, const char **pzOriginTab, const char **pzOriginCol ){ char const *zType = 0; char const *zOriginDb = 0; char const *zOriginTab = 0; char const *zOriginCol = 0; int j; if( NEVER(pExpr==0) || pNC->pSrcList==0 ) return 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. */ NameContext sNC; Expr *p = pS->pEList->a[iCol].pExpr; sNC.pSrcList = pS->pSrc; sNC.pNext = pNC; sNC.pParse = pNC->pParse; zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol); } }else if( ALWAYS(pTab->pSchema) ){ /* A real table */ assert( !pS ); if( iCol<0 ) iCol = pTab->iPKey; assert( iCol==-1 || (iCol>=0 && iColnCol) ); if( iCol<0 ){ zType = "INTEGER"; zOriginCol = "rowid"; }else{ zType = pTab->aCol[iCol].zType; zOriginCol = pTab->aCol[iCol].zName; } zOriginTab = pTab->zName; if( pNC->pParse ){ int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema); zOriginDb = pNC->pParse->db->aDb[iDb].zName; } } 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, &zOriginDb, &zOriginTab, &zOriginCol); break; } #endif } if( pzOriginDb ){ assert( pzOriginTab && pzOriginCol ); *pzOriginDb = zOriginDb; *pzOriginTab = zOriginTab; *pzOriginCol = zOriginCol; } 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); /* 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); #endif sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT); } #endif /* 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 || NEVER(v==0) || db->mallocFailed ) return; 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) && pTabList ){ 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{ sqlite3VdbeSetColName(v, i, COLNAME_NAME, sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC); } } generateColumnTypes(pParse, pTabList, pEList); } /* ** Given a 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. */ static int selectColumnsFromExprList( Parse *pParse, /* Parsing context */ ExprList *pEList, /* Expr list from which to derive column names */ int *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 */ int 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[] */ *pnCol = nCol = pEList->nExpr; aCol = *paCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol); if( aCol==0 ) return SQLITE_NOMEM; for(i=0, pCol=aCol; ia[i].pExpr; assert( p->pRight==0 || ExprHasProperty(p->pRight, EP_IntValue) || p->pRight->u.zToken==0 || p->pRight->u.zToken[0]!=0 ); if( (zName = pEList->a[i].zName)!=0 ){ /* If the column contains an "AS " phrase, use as the name */ zName = sqlite3DbStrDup(db, zName); }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; 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 = sqlite3MPrintf(db, "%s", iCol>=0 ? pTab->aCol[iCol].zName : "rowid"); }else if( pColExpr->op==TK_ID ){ assert( !ExprHasProperty(pColExpr, EP_IntValue) ); zName = sqlite3MPrintf(db, "%s", pColExpr->u.zToken); }else{ /* Use the original text of the column expression as its name */ zName = sqlite3MPrintf(db, "%s", pEList->a[i].zSpan); } } if( db->mallocFailed ){ sqlite3DbFree(db, zName); break; } /* Make sure the column name is unique. If the name is not unique, ** append a integer to the name so that it becomes unique. */ nName = sqlite3Strlen30(zName); for(j=cnt=0; jzName = zName; } if( db->mallocFailed ){ for(j=0; jdb; NameContext sNC; Column *pCol; CollSeq *pColl; int i; Expr *p; struct ExprList_item *a; assert( pSelect!=0 ); assert( (pSelect->selFlags & SF_Resolved)!=0 ); assert( 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=aCol; izType = sqlite3DbStrDup(db, columnType(&sNC, p, 0, 0, 0)); pCol->affinity = sqlite3ExprAffinity(p); if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_NONE; pColl = sqlite3ExprCollSeq(pParse, p); if( pColl ){ pCol->zColl = sqlite3DbStrDup(db, pColl->zName); } } } /* ** 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.bEnabled==0 ); pTab->nRef = 1; pTab->zName = 0; pTab->nRowEst = 1000000; selectColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol); selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, 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. */ Vdbe *sqlite3GetVdbe(Parse *pParse){ Vdbe *v = pParse->pVdbe; if( v==0 ){ v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db); #ifndef SQLITE_OMIT_TRACE if( v ){ sqlite3VdbeAddOp0(v, OP_Trace); } #endif } return v; } /* ** 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 ** (usually but not always -1) prior to calling this routine. ** 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 addr1, n; if( p->iLimit ) return; /* ** "LIMIT -1" always shows all rows. There is some ** contraversy 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); if( NEVER(v==0) ) return; /* VDBE should have already been allocated */ if( sqlite3ExprIsInteger(p->pLimit, &n) ){ sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit); VdbeComment((v, "LIMIT counter")); if( n==0 ){ sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak); }else{ if( p->nSelectRow > (double)n ) p->nSelectRow = (double)n; } }else{ sqlite3ExprCode(pParse, p->pLimit, iLimit); sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeComment((v, "LIMIT counter")); sqlite3VdbeAddOp2(v, OP_IfZero, iLimit, iBreak); } 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); VdbeComment((v, "OFFSET counter")); addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iOffset); sqlite3VdbeAddOp2(v, OP_Integer, 0, iOffset); sqlite3VdbeJumpHere(v, addr1); sqlite3VdbeAddOp3(v, OP_Add, iLimit, iOffset, iOffset+1); VdbeComment((v, "LIMIT+OFFSET")); addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iLimit); sqlite3VdbeAddOp2(v, OP_Integer, -1, iOffset+1); sqlite3VdbeJumpHere(v, addr1); } } } #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 ); if( pRet==0 && iColpEList->nExpr ){ pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr); } return pRet; } #endif /* SQLITE_OMIT_COMPOUND_SELECT */ /* Forward reference */ 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 */ ); #ifndef SQLITE_OMIT_COMPOUND_SELECT /* ** 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; /* EQP id of left-hand query */ int iSub2; /* 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 */ db = pParse->db; pPrior = p->pPrior; assert( pPrior->pRightmost!=pPrior ); assert( pPrior->pRightmost==p->pRightmost ); 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.iParm, p->pEList->nExpr); sqlite3VdbeChangeP5(v, BTREE_UNORDERED); dest.eDest = SRT_Table; } /* Make sure all SELECTs in the statement have the same number of elements ** in their result sets. */ assert( p->pEList && pPrior->pEList ); if( p->pEList->nExpr!=pPrior->pEList->nExpr ){ sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s" " do not have the same number of result columns", selectOpName(p->op)); rc = 1; goto multi_select_end; } /* Compound SELECTs that have an ORDER BY clause are handled separately. */ if( p->pOrderBy ){ return multiSelectOrderBy(pParse, p, pDest); } /* Generate code for the left and right SELECT statements. */ switch( p->op ){ case TK_ALL: { int addr = 0; int nLimit; assert( !pPrior->pLimit ); 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_IfZero, p->iLimit); VdbeComment((v, "Jump ahead if LIMIT reached")); } explainSetInteger(iSub2, pParse->iNextSelectId); rc = sqlite3Select(pParse, p, &dest); testcase( rc!=SQLITE_OK ); pDelete = p->pPrior; p->pPrior = pPrior; p->nSelectRow += pPrior->nSelectRow; if( pPrior->pLimit && sqlite3ExprIsInteger(pPrior->pLimit, &nLimit) && p->nSelectRow > (double)nLimit ){ p->nSelectRow = (double)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 && ALWAYS(!p->pLimit &&!p->pOffset) ){ /* We can reuse a temporary table generated by a SELECT to our ** right. */ assert( p->pRightmost!=p ); /* Can only happen for leftward elements ** of a 3-way or more compound */ assert( p->pLimit==0 ); /* Not allowed on leftward elements */ assert( p->pOffset==0 ); /* Not allowed on leftward elements */ unionTab = dest.iParm; }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; p->pRightmost->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 += 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.iParm || 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, 0, pFirst->pEList); } iBreak = sqlite3VdbeMakeLabel(v); iCont = sqlite3VdbeMakeLabel(v); computeLimitRegisters(pParse, p, iBreak); sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); iStart = sqlite3VdbeCurrentAddr(v); selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr, 0, -1, &dest, iCont, iBreak); sqlite3VdbeResolveLabel(v, iCont); sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); 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; p->pRightmost->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.iParm = 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, 0, pFirst->pEList); } iBreak = sqlite3VdbeMakeLabel(v); iCont = sqlite3VdbeMakeLabel(v); computeLimitRegisters(pParse, p, iBreak); sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); r1 = sqlite3GetTempReg(pParse); iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1); sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0); sqlite3ReleaseTempReg(pParse, r1); selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr, 0, -1, &dest, iCont, iBreak); sqlite3VdbeResolveLabel(v, iCont); sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); 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->pRightmost==p ); nCol = p->pEList->nExpr; pKeyInfo = sqlite3DbMallocZero(db, sizeof(*pKeyInfo)+nCol*(sizeof(CollSeq*) + 1)); if( !pKeyInfo ){ rc = SQLITE_NOMEM; goto multi_select_end; } pKeyInfo->enc = ENC(db); pKeyInfo->nField = (u16)nCol; 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*)pKeyInfo, P4_KEYINFO); pLoop->addrOpenEphm[i] = -1; } } sqlite3DbFree(db, pKeyInfo); } multi_select_end: pDest->iMem = dest.iMem; pDest->nMem = dest.nMem; sqlite3SelectDelete(db, pDelete); return rc; } #endif /* SQLITE_OMIT_COMPOUND_SELECT */ /* ** Code an output subroutine for a coroutine implementation of a ** SELECT statment. ** ** The data to be output is contained in pIn->iMem. There are ** pIn->nMem 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 p4type, /* The p4 type for pKeyInfo */ 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 j1, j2; j1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev); j2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iMem, regPrev+1, pIn->nMem, (char*)pKeyInfo, p4type); sqlite3VdbeAddOp3(v, OP_Jump, j2+2, iContinue, j2+2); sqlite3VdbeJumpHere(v, j1); sqlite3ExprCodeCopy(pParse, pIn->iMem, regPrev+1, pIn->nMem); sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev); } if( pParse->db->mallocFailed ) return 0; /* Suppress the the first OFFSET entries if there is an OFFSET clause */ codeOffset(v, p, iContinue); switch( pDest->eDest ){ /* Store the result as data using a unique key. */ case SRT_Table: case SRT_EphemTab: { int r1 = sqlite3GetTempReg(pParse); int r2 = sqlite3GetTempReg(pParse); testcase( pDest->eDest==SRT_Table ); testcase( pDest->eDest==SRT_EphemTab ); sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iMem, pIn->nMem, r1); sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iParm, r2); sqlite3VdbeAddOp3(v, OP_Insert, pDest->iParm, 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->nMem==1 ); p->affinity = sqlite3CompareAffinity(p->pEList->a[0].pExpr, pDest->affinity); r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iMem, 1, r1, &p->affinity, 1); sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, 1); sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iParm, r1); sqlite3ReleaseTempReg(pParse, r1); break; } #if 0 /* Never occurs on an ORDER BY query */ /* If any row exist in the result set, record that fact and abort. */ case SRT_Exists: { sqlite3VdbeAddOp2(v, OP_Integer, 1, pDest->iParm); /* The LIMIT clause will terminate the loop for us */ break; } #endif /* 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->nMem==1 ); sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iParm, 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->iMem. Then the co-routine yields. */ case SRT_Coroutine: { if( pDest->iMem==0 ){ pDest->iMem = sqlite3GetTempRange(pParse, pIn->nMem); pDest->nMem = pIn->nMem; } sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iMem, pDest->nMem); sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm); 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->iMem, pIn->nMem); sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, pIn->nMem); break; } } /* Jump to the end of the loop if the LIMIT is reached. */ if( p->iLimit ){ sqlite3VdbeAddOp3(v, OP_IfZero, p->iLimit, iBreak, -1); } /* 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 regEofA; /* Flag to indicate when select-A is complete */ int regAddrB; /* Address register for select-B coroutine */ int regEofB; /* Flag to indicate when select-B is complete */ 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 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 j1; /* 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; jiCol>0 ); if( pItem->iCol==i ) break; } if( j==nOrderBy ){ Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0); if( pNew==0 ) return SQLITE_NOMEM; pNew->flags |= EP_IntValue; pNew->u.iValue = i; pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew); pOrderBy->a[nOrderBy++].iCol = (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 = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy); if( aPermute ){ struct ExprList_item *pItem; for(i=0, pItem=pOrderBy->a; iiCol>0 && pItem->iCol<=p->pEList->nExpr ); aPermute[i] = pItem->iCol - 1; } pKeyMerge = sqlite3DbMallocRaw(db, sizeof(*pKeyMerge)+nOrderBy*(sizeof(CollSeq*)+1)); if( pKeyMerge ){ pKeyMerge->aSortOrder = (u8*)&pKeyMerge->aColl[nOrderBy]; pKeyMerge->nField = (u16)nOrderBy; pKeyMerge->enc = ENC(db); for(i=0; ia[i].pExpr; if( pTerm->flags & EP_ExpCollate ){ pColl = pTerm->pColl; }else{ pColl = multiSelectCollSeq(pParse, p, aPermute[i]); pTerm->flags |= EP_ExpCollate; pTerm->pColl = pColl; } pKeyMerge->aColl[i] = pColl; pKeyMerge->aSortOrder[i] = pOrderBy->a[i].sortOrder; } } }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 = sqlite3GetTempRange(pParse, nExpr+1); sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev); pKeyDup = sqlite3DbMallocZero(db, sizeof(*pKeyDup) + nExpr*(sizeof(CollSeq*)+1) ); if( pKeyDup ){ pKeyDup->aSortOrder = (u8*)&pKeyDup->aColl[nExpr]; pKeyDup->nField = (u16)nExpr; pKeyDup->enc = ENC(db); 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; 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; regEofA = ++pParse->nMem; regAddrB = ++pParse->nMem; regEofB = ++pParse->nMem; regOutA = ++pParse->nMem; regOutB = ++pParse->nMem; sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA); sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB); /* Jump past the various subroutines and coroutines to the main ** merge loop */ j1 = sqlite3VdbeAddOp0(v, OP_Goto); addrSelectA = sqlite3VdbeCurrentAddr(v); /* Generate a coroutine to evaluate the SELECT statement to the ** left of the compound operator - the "A" select. */ VdbeNoopComment((v, "Begin coroutine for left SELECT")); pPrior->iLimit = regLimitA; explainSetInteger(iSub1, pParse->iNextSelectId); sqlite3Select(pParse, pPrior, &destA); sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofA); sqlite3VdbeAddOp1(v, OP_Yield, regAddrA); VdbeNoopComment((v, "End coroutine for left SELECT")); /* Generate a coroutine to evaluate the SELECT statement on ** the right - the "B" select */ addrSelectB = sqlite3VdbeCurrentAddr(v); VdbeNoopComment((v, "Begin coroutine for 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; sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofB); sqlite3VdbeAddOp1(v, OP_Yield, regAddrB); VdbeNoopComment((v, "End coroutine for right SELECT")); /* 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, P4_KEYINFO_HANDOFF, 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, P4_KEYINFO_STATIC, labelEnd); } /* Generate a subroutine to run when the results from select A ** are exhausted and only data in select B remains. */ VdbeNoopComment((v, "eof-A subroutine")); if( op==TK_EXCEPT || op==TK_INTERSECT ){ addrEofA = sqlite3VdbeAddOp2(v, OP_Goto, 0, labelEnd); }else{ addrEofA = sqlite3VdbeAddOp2(v, OP_If, regEofB, labelEnd); sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB); sqlite3VdbeAddOp1(v, OP_Yield, regAddrB); sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA); 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_If, regEofA, labelEnd); sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA); sqlite3VdbeAddOp1(v, OP_Yield, regAddrA); sqlite3VdbeAddOp2(v, OP_Goto, 0, 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); } sqlite3VdbeAddOp1(v, OP_Yield, regAddrB); sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB); sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr); /* This code runs once to initialize everything. */ sqlite3VdbeJumpHere(v, j1); sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofA); sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofB); sqlite3VdbeAddOp2(v, OP_Gosub, regAddrA, addrSelectA); sqlite3VdbeAddOp2(v, OP_Gosub, regAddrB, addrSelectB); sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA); sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB); /* Implement the main merge loop */ sqlite3VdbeResolveLabel(v, labelCmpr); sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY); sqlite3VdbeAddOp4(v, OP_Compare, destA.iMem, destB.iMem, nOrderBy, (char*)pKeyMerge, P4_KEYINFO_HANDOFF); sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB); /* Release temporary registers */ if( regPrev ){ sqlite3ReleaseTempRange(pParse, regPrev, nOrderBy+1); } /* 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, 0, 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; /*** TBD: Insert subroutine calls to close cursors on incomplete **** subqueries ****/ explainComposite(pParse, p->op, iSub1, iSub2, 0); return SQLITE_OK; } #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 *); /* ** 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); if( pNew && pExpr->pColl ){ pNew->pColl = pExpr->pColl; } 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); }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 */ ){ SrcList *pSrc; struct SrcList_item *pItem; int i; if( !p ) return; 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); substSelect(db, p->pPrior, iTable, pEList); pSrc = p->pSrc; assert( pSrc ); /* Even for (SELECT 1) we have: pSrc!=0 but pSrc->nSrc==0 */ if( ALWAYS(pSrc) ){ for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ substSelect(db, pItem->pSelect, iTable, pEList); } } } #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) /* ** This routine attempts to flatten subqueries in order to speed ** execution. It 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 simpification 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 the outer query is not a join. ** ** (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. ** ** (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. ** ** (10) 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 ** * has no other tables or sub-selects in the FROM clause. ** ** 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. ** ** (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 ** have other optimizations in mind to deal with that case. ** ** 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; 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( db->flags & 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( isAgg && subqueryIsAgg ) return 0; /* Restriction (1) */ if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; /* Restriction (2) */ pSubSrc = pSub->pSrc; assert( pSubSrc ); /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants, ** not arbitrary expresssions, 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->pRightmost && 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) */ /* 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->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 ); if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0 || (pSub1->pPrior && pSub1->op!=TK_ALL) || NEVER(pSub1->pSrc==0) || pSub1->pSrc->nSrc!=1 ){ return 0; } } /* Restriction 18. */ if( p->pOrderBy ){ int ii; for(ii=0; iipOrderBy->nExpr; ii++){ if( p->pOrderBy->a[ii].iCol==0 ) return 0; } } } /***** If we reach this point, flattening is permitted. *****/ /* Authorize the subquery */ pParse->zAuthContext = pSubitem->zName; sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0); 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; Select *pPrior = p->pPrior; p->pOrderBy = 0; p->pSrc = 0; p->pPrior = 0; p->pLimit = 0; pNew = sqlite3SelectDup(db, p, 0); p->pLimit = pLimit; p->pOrderBy = pOrderBy; p->pSrc = pSrc; p->op = TK_ALL; p->pRightmost = 0; if( pNew==0 ){ pNew = pPrior; }else{ pNew->pPrior = pPrior; pNew->pRightmost = 0; } p->pPrior = 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->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 out query 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); pSrc->a[i+iFrom] = pSubSrc->a[i]; memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i])); } pSrc->a[iFrom].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 ){ const char *zSpan = pList->a[i].zSpan; if( ALWAYS(zSpan) ){ pList->a[i].zName = sqlite3DbStrDup(db, zSpan); } } } substExprList(db, pParent->pEList, iParent, pSub->pEList); if( isAgg ){ substExprList(db, pParent->pGroupBy, iParent, pSub->pEList); pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList); } if( pSub->pOrderBy ){ assert( pParent->pOrderBy==0 ); pParent->pOrderBy = pSub->pOrderBy; pSub->pOrderBy = 0; }else if( pParent->pOrderBy ){ substExprList(db, pParent->pOrderBy, iParent, pSub->pEList); } if( pSub->pWhere ){ pWhere = sqlite3ExprDup(db, pSub->pWhere, 0); }else{ pWhere = 0; } if( subqueryIsAgg ){ assert( pParent->pHaving==0 ); pParent->pHaving = pParent->pWhere; pParent->pWhere = pWhere; pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList); 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 = substExpr(db, pParent->pWhere, iParent, pSub->pEList); pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere); } /* 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); return 1; } #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ /* ** Analyze the SELECT statement passed as an argument to see if it ** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if ** it is, or 0 otherwise. At present, a query is considered to be ** a min()/max() query if: ** ** 1. There is a single object in the FROM clause. ** ** 2. There is a single expression in the result set, and it is ** either min(x) or max(x), where x is a column reference. */ static u8 minMaxQuery(Select *p){ Expr *pExpr; ExprList *pEList = p->pEList; if( pEList->nExpr!=1 ) return WHERE_ORDERBY_NORMAL; pExpr = pEList->a[0].pExpr; if( pExpr->op!=TK_AGG_FUNCTION ) return 0; if( NEVER(ExprHasProperty(pExpr, EP_xIsSelect)) ) return 0; pEList = pExpr->x.pList; if( pEList==0 || pEList->nExpr!=1 ) return 0; if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return WHERE_ORDERBY_NORMAL; assert( !ExprHasProperty(pExpr, EP_IntValue) ); if( sqlite3StrICmp(pExpr->u.zToken,"min")==0 ){ return WHERE_ORDERBY_MIN; }else if( sqlite3StrICmp(pExpr->u.zToken,"max")==0 ){ return WHERE_ORDERBY_MAX; } return WHERE_ORDERBY_NORMAL; } /* ** The select statement passed as the first argument is an aggregate query. ** The second argment 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( (pAggInfo->aFunc[0].pFunc->flags&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->zIndex ){ Table *pTab = pFrom->pTab; char *zIndex = pFrom->zIndex; Index *pIdx; for(pIdx=pTab->pIndex; pIdx && sqlite3StrICmp(pIdx->zName, zIndex); pIdx=pIdx->pNext ); if( !pIdx ){ sqlite3ErrorMsg(pParse, "no such index: %s", zIndex, 0); pParse->checkSchema = 1; return SQLITE_ERROR; } pFrom->pIndex = pIdx; } return SQLITE_OK; } /* ** 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 presistent representation ** of the view. ** ** (3) Add terms to the WHERE clause to accomodate 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; if( db->mallocFailed ){ return WRC_Abort; } if( NEVER(p->pSrc==0) || (p->selFlags & SF_Expanded)!=0 ){ return WRC_Prune; } p->selFlags |= SF_Expanded; pTabList = p->pSrc; pEList = p->pEList; /* 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; if( pFrom->pTab!=0 ){ /* This statement has already been prepared. There is no need ** to go further. */ assert( i==0 ); return WRC_Prune; } 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 ); sqlite3WalkSelect(pWalker, pSel); pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table)); if( pTab==0 ) return WRC_Abort; pTab->nRef = 1; pTab->zName = sqlite3MPrintf(db, "sqlite_subquery_%p_", (void*)pTab); while( pSel->pPrior ){ pSel = pSel->pPrior; } selectColumnsFromExprList(pParse, pSel->pEList, &pTab->nCol, &pTab->aCol); pTab->iPKey = -1; pTab->nRowEst = 1000000; pTab->tabFlags |= TF_Ephemeral; #endif }else{ /* An ordinary table or view name in the FROM clause */ assert( pFrom->pTab==0 ); pFrom->pTab = pTab = sqlite3LocateTable(pParse,0,pFrom->zName,pFrom->zDatabase); if( pTab==0 ) return WRC_Abort; pTab->nRef++; #if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE) if( pTab->pSelect || IsVirtual(pTab) ){ /* We reach here if the named table is a really a view */ if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort; assert( pFrom->pSelect==0 ); pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0); sqlite3WalkSelect(pWalker, pFrom->pSelect); } #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_ALL operator for each "*" that it found in the column list. ** The following code just has to locate the TK_ALL 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++){ Expr *pE = pEList->a[k].pExpr; if( pE->op==TK_ALL ) 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_ALL ) 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++){ Expr *pE = a[k].pExpr; assert( pE->op!=TK_DOT || pE->pRight!=0 ); if( pE->op!=TK_ALL && (pE->op!=TK_DOT || pE->pRight->op!=TK_ALL) ){ /* 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; /* 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; }else{ zTName = 0; } for(i=0, pFrom=pTabList->a; inSrc; i++, pFrom++){ Table *pTab = pFrom->pTab; char *zTabName = pFrom->zAlias; if( zTabName==0 ){ zTabName = pTab->zName; } if( db->mallocFailed ) break; if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){ continue; } tableSeen = 1; for(j=0; jnCol; j++){ Expr *pExpr, *pRight; 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 */ /* If a column is marked as 'hidden' (currently only possible ** for virtual tables), do not include it in the expanded ** result-set list. */ if( IsHiddenColumn(&pTab->aCol[j]) ){ assert(IsVirtual(pTab)); continue; } if( i>0 && zTName==0 ){ if( (pFrom->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( longNames ){ zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName); zToFree = zColname; } }else{ pExpr = pRight; } pNew = sqlite3ExprListAppend(pParse, pNew, pExpr); sColname.z = zColname; sColname.n = sqlite3Strlen30(zColname); sqlite3ExprListSetName(pParse, pNew, &sColname, 0); 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"); } #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. */ static int exprWalkNoop(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; w.xSelectCallback = selectExpander; w.xExprCallback = exprWalkNoop; w.pParse = pParse; 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 int selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){ Parse *pParse; int i; SrcList *pTabList; struct SrcList_item *pFrom; assert( p->selFlags & SF_Resolved ); if( (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; if( ALWAYS(pTab!=0) && (pTab->tabFlags & TF_Ephemeral)!=0 ){ /* A sub-query in the FROM clause of a SELECT */ Select *pSel = pFrom->pSelect; assert( pSel ); while( pSel->pPrior ) pSel = pSel->pPrior; selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSel); } } } return WRC_Continue; } #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; w.xSelectCallback = selectAddSubqueryTypeInfo; w.xExprCallback = exprWalkNoop; w.pParse = pParse; sqlite3WalkSelect(&w, pSelect); #endif } /* ** This routine sets of 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( 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 simply 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; if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){ return; } for(i=0; inColumn; i++){ sqlite3VdbeAddOp2(v, OP_Null, 0, pAggInfo->aCol[i].iMem); } for(pFunc=pAggInfo->aFunc, i=0; inFunc; i++, pFunc++){ sqlite3VdbeAddOp2(v, OP_Null, 0, pFunc->iMem); 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); sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF); } } } } /* ** 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; struct AggInfo_func *pF; struct AggInfo_col *pC; pAggInfo->directMode = 1; sqlite3ExprCacheClear(pParse); 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, 1); }else{ nArg = 0; regAgg = 0; } if( pF->iDistinct>=0 ){ addrNext = sqlite3VdbeMakeLabel(v); assert( nArg==1 ); codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg); } if( pF->pFunc->flags & 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; } sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ); } sqlite3VdbeAddOp4(v, OP_AggStep, 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. */ sqlite3ExprCacheClear(pParse); for(i=0, pC=pAggInfo->aCol; inAccumulator; i++, pC++){ sqlite3ExprCode(pParse, pC->pExpr, pC->iMem); } pAggInfo->directMode = 0; sqlite3ExprCacheClear(pParse); } /* ** Generate code for the SELECT statement given in the p argument. ** ** The results are distributed in various ways depending on the ** contents of the SelectDest structure pointed to by argument pDest ** as follows: ** ** pDest->eDest Result ** ------------ ------------------------------------------- ** SRT_Output Generate a row of output (using the OP_ResultRow ** opcode) for each row in the result set. ** ** SRT_Mem Only valid if the result is a single column. ** Store the first column of the first result row ** in register pDest->iParm then abandon the rest ** of the query. This destination implies "LIMIT 1". ** ** SRT_Set The result must be a single column. Store each ** row of result as the key in table pDest->iParm. ** Apply the affinity pDest->affinity before storing ** results. Used to implement "IN (SELECT ...)". ** ** SRT_Union Store results as a key in a temporary table pDest->iParm. ** ** SRT_Except Remove results from the temporary table pDest->iParm. ** ** SRT_Table Store results in temporary table pDest->iParm. ** This is like SRT_EphemTab except that the table ** is assumed to already be open. ** ** SRT_EphemTab Create an temporary table pDest->iParm and store ** the result there. The cursor is left open after ** returning. This is like SRT_Table except that ** this destination uses OP_OpenEphemeral to create ** the table first. ** ** SRT_Coroutine Generate a co-routine that returns a new row of ** results each time it is invoked. The entry point ** of the co-routine is stored in register pDest->iParm. ** ** SRT_Exists Store a 1 in memory cell pDest->iParm if the result ** set is not empty. ** ** SRT_Discard Throw the results away. This is used by SELECT ** statements within triggers whose only purpose is ** the side-effects of functions. ** ** 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; /* List of columns to extract. */ SrcList *pTabList; /* List of tables to select from */ Expr *pWhere; /* The WHERE clause. May be NULL */ ExprList *pOrderBy; /* The ORDER BY clause. May be NULL */ ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */ Expr *pHaving; /* The HAVING clause. May be NULL */ int isDistinct; /* True if the DISTINCT keyword is present */ int distinct; /* Table to use for the distinct set */ int rc = 1; /* Value to return from this function */ int addrSortIndex; /* Address of an OP_OpenEphemeral instruction */ 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( IgnorableOrderby(pDest) ){ assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union || pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard); /* 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); pOrderBy = p->pOrderBy; pTabList = p->pSrc; pEList = p->pEList; if( pParse->nErr || db->mallocFailed ){ goto select_end; } isAgg = (p->selFlags & SF_Aggregate)!=0; assert( pEList!=0 ); /* Begin generating code. */ v = sqlite3GetVdbe(pParse); if( v==0 ) goto select_end; /* If writing to memory or generating a set ** only a single column may be output. */ #ifndef SQLITE_OMIT_SUBQUERY if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){ goto select_end; } #endif /* Generate code for all sub-queries in the FROM clause */ #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) for(i=0; !p->pPrior && inSrc; i++){ struct SrcList_item *pItem = &pTabList->a[i]; SelectDest dest; Select *pSub = pItem->pSelect; int isAggSub; if( pSub==0 || pItem->isPopulated ) continue; /* Increment Parse.nHeight by the height of the largest expression ** tree refered 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); /* Check to see if the subquery can be absorbed into the parent. */ isAggSub = (pSub->selFlags & SF_Aggregate)!=0; if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){ if( isAggSub ){ isAgg = 1; p->selFlags |= SF_Aggregate; } i = -1; }else{ sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor); assert( pItem->isPopulated==0 ); explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId); sqlite3Select(pParse, pSub, &dest); pItem->isPopulated = 1; pItem->pTab->nRowEst = (unsigned)pSub->nSelectRow; } if( /*pParse->nErr ||*/ db->mallocFailed ){ goto select_end; } pParse->nHeight -= sqlite3SelectExprHeight(p); pTabList = p->pSrc; if( !IgnorableOrderby(pDest) ){ pOrderBy = p->pOrderBy; } } pEList = p->pEList; #endif pWhere = p->pWhere; pGroupBy = p->pGroupBy; pHaving = p->pHaving; isDistinct = (p->selFlags & SF_Distinct)!=0; #ifndef SQLITE_OMIT_COMPOUND_SELECT /* If there is are a sequence of queries, do the earlier ones first. */ if( p->pPrior ){ if( p->pRightmost==0 ){ Select *pLoop, *pRight = 0; int cnt = 0; int mxSelect; for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){ pLoop->pRightmost = p; pLoop->pNext = pRight; pRight = pLoop; } mxSelect = db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT]; if( mxSelect && cnt>mxSelect ){ sqlite3ErrorMsg(pParse, "too many terms in compound SELECT"); goto select_end; } } rc = multiSelect(pParse, p, pDest); explainSetInteger(pParse->iSelectId, iRestoreSelectId); return rc; } #endif /* If possible, rewrite the query to use GROUP BY instead of DISTINCT. ** GROUP BY might use an index, DISTINCT never does. */ assert( p->pGroupBy==0 || (p->selFlags & SF_Aggregate)!=0 ); if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct ){ p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0); pGroupBy = p->pGroupBy; p->selFlags &= ~SF_Distinct; } /* If there is both a GROUP BY and an ORDER BY clause and they are ** identical, then disable the ORDER BY clause since the GROUP BY ** will cause elements to come out in the correct order. 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( sqlite3ExprListCompare(p->pGroupBy, pOrderBy)==0 && (db->flags & SQLITE_GroupByOrder)==0 ){ pOrderBy = 0; } /* If there is an ORDER BY clause, then this sorting ** 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 addrSortIndex ** variable is used to facilitate that change. */ if( pOrderBy ){ KeyInfo *pKeyInfo; pKeyInfo = keyInfoFromExprList(pParse, pOrderBy); pOrderBy->iECursor = pParse->nTab++; p->addrOpenEphm[2] = addrSortIndex = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pOrderBy->iECursor, pOrderBy->nExpr+2, 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF); }else{ addrSortIndex = -1; } /* If the output is destined for a temporary table, open that table. */ if( pDest->eDest==SRT_EphemTab ){ sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iParm, pEList->nExpr); } /* Set the limiter. */ iEnd = sqlite3VdbeMakeLabel(v); p->nSelectRow = (double)LARGEST_INT64; computeLimitRegisters(pParse, p, iEnd); /* Open a virtual index to use for the distinct set. */ if( p->selFlags & SF_Distinct ){ KeyInfo *pKeyInfo; assert( isAgg || pGroupBy ); distinct = pParse->nTab++; pKeyInfo = keyInfoFromExprList(pParse, p->pEList); sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF); sqlite3VdbeChangeP5(v, BTREE_UNORDERED); }else{ distinct = -1; } /* Aggregate and non-aggregate queries are handled differently */ if( !isAgg && pGroupBy==0 ){ /* This case is for non-aggregate queries ** Begin the database scan */ pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, 0); if( pWInfo==0 ) goto select_end; if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut; /* 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( addrSortIndex>=0 && pOrderBy==0 ){ sqlite3VdbeChangeToNoop(v, addrSortIndex, 1); p->addrOpenEphm[2] = -1; } /* Use the standard inner loop */ assert(!isDistinct); selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, -1, pDest, pWInfo->iContinue, pWInfo->iBreak); /* End the database scan loop. */ sqlite3WhereEnd(pWInfo); }else{ /* This is the processing for aggregate queries */ 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 */ /* 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->iAlias = 0; } for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){ pItem->iAlias = 0; } if( p->nSelectRow>(double)100 ) p->nSelectRow = (double)100; }else{ p->nSelectRow = (double)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.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0; sAggInfo.pGroupBy = pGroupBy; sqlite3ExprAnalyzeAggList(&sNC, pEList); sqlite3ExprAnalyzeAggList(&sNC, pOrderBy); if( pHaving ){ sqlite3ExprAnalyzeAggregates(&sNC, pHaving); } sAggInfo.nAccumulator = sAggInfo.nColumn; for(i=0; ix.pList); } 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 j1; /* 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 OpenEphemeral instruction ** will be converted into a Noop. */ sAggInfo.sortingIdx = pParse->nTab++; pKeyInfo = keyInfoFromExprList(pParse, pGroupBy); addrSortingIdx = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, sAggInfo.sortingIdx, sAggInfo.nSortingColumn, 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF); /* 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")); /* 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); if( pWInfo==0 ) goto select_end; if( pGroupBy==0 ){ /* 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 */ pGroupBy = p->pGroupBy; 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, isDistinct && !(p->selFlags&SF_Distinct)?"DISTINCT":"GROUP BY"); groupBySort = 1; nGroupBy = pGroupBy->nExpr; nCol = nGroupBy + 1; j = nGroupBy+1; for(i=0; i=j ){ nCol++; j++; } } regBase = sqlite3GetTempRange(pParse, nCol); sqlite3ExprCacheClear(pParse); sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0); sqlite3VdbeAddOp2(v, OP_Sequence, sAggInfo.sortingIdx,regBase+nGroupBy); j = nGroupBy+1; for(i=0; iiSorterColumn>=j ){ int r1 = j + regBase; int r2; r2 = sqlite3ExprCodeGetColumn(pParse, pCol->pTab, pCol->iColumn, pCol->iTable, r1); if( r1!=r2 ){ sqlite3VdbeAddOp2(v, OP_SCopy, r2, r1); } j++; } } regRecord = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord); sqlite3VdbeAddOp2(v, OP_IdxInsert, sAggInfo.sortingIdx, regRecord); sqlite3ReleaseTempReg(pParse, regRecord); sqlite3ReleaseTempRange(pParse, regBase, nCol); sqlite3WhereEnd(pWInfo); sqlite3VdbeAddOp2(v, OP_Sort, sAggInfo.sortingIdx, addrEnd); VdbeComment((v, "GROUP BY sort")); sAggInfo.useSortingIdx = 1; sqlite3ExprCacheClear(pParse); } /* 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); for(j=0; jnExpr; j++){ if( groupBySort ){ sqlite3VdbeAddOp3(v, OP_Column, sAggInfo.sortingIdx, j, iBMem+j); }else{ sAggInfo.directMode = 1; sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j); } } sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr, (char*)pKeyInfo, P4_KEYINFO); j1 = sqlite3VdbeCurrentAddr(v); sqlite3VdbeAddOp3(v, OP_Jump, j1+1, 0, j1+1); /* 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); 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, j1); updateAccumulator(pParse, &sAggInfo); sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag); VdbeComment((v, "indicate data in accumulator")); /* End of the loop */ if( groupBySort ){ sqlite3VdbeAddOp2(v, OP_Next, sAggInfo.sortingIdx, addrTopOfLoop); }else{ sqlite3WhereEnd(pWInfo); sqlite3VdbeChangeToNoop(v, addrSortingIdx, 1); } /* Output the final row of result */ sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow); VdbeComment((v, "output final row")); /* Jump over the subroutines */ sqlite3VdbeAddOp2(v, OP_Goto, 0, 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); 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, 0, 0, pOrderBy, distinct, 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 least amount of columns. If ** there is such an index, and it has less columns than the table ** does, then we can assume that it consumes less space on disk and ** will therefore be cheaper to scan to determine the query result. ** In this case set iRoot to the root page number of the index b-tree ** and pKeyInfo to the KeyInfo structure required to navigate the ** index. ** ** In practice the KeyInfo structure will not be used. It is only ** passed to keep OP_OpenRead happy. */ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ if( !pBest || pIdx->nColumnnColumn ){ pBest = pIdx; } } if( pBest && pBest->nColumnnCol ){ iRoot = pBest->tnum; pKeyInfo = sqlite3IndexKeyinfo(pParse, pBest); } /* Open a read-only cursor, execute the OP_Count, close the cursor. */ sqlite3VdbeAddOp3(v, OP_OpenRead, iCsr, iRoot, iDb); if( pKeyInfo ){ sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO_HANDOFF); } sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem); sqlite3VdbeAddOp1(v, OP_Close, iCsr); }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 behaviour 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 = minMaxQuery(p); if( flag ){ assert( !ExprHasProperty(p->pEList->a[0].pExpr, EP_xIsSelect) ); pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->x.pList,0); pDel = pMinMax; if( pMinMax && !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, flag); if( pWInfo==0 ){ sqlite3ExprListDelete(db, pDel); goto select_end; } updateAccumulator(pParse, &sAggInfo); if( !pMinMax && flag ){ sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak); VdbeComment((v, "%s() by index", (flag==WHERE_ORDERBY_MIN?"min":"max"))); } sqlite3WhereEnd(pWInfo); finalizeAggFunctions(pParse, &sAggInfo); } pOrderBy = 0; sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL); selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1, pDest, addrEnd, addrEnd); sqlite3ExprListDelete(db, pDel); } sqlite3VdbeResolveLabel(v, addrEnd); } /* endif aggregate query */ if( distinct>=0 ){ 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( pOrderBy ){ explainTempTable(pParse, "ORDER BY"); generateSortTail(pParse, p, v, pEList->nExpr, pDest); } /* Jump here to skip this query */ sqlite3VdbeResolveLabel(v, iEnd); /* The SELECT was successfully coded. Set the return code to 0 ** to indicate no errors. */ rc = 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); return rc; } #if defined(SQLITE_DEBUG) /* ******************************************************************************* ** The following code is used for testing and debugging only. The code ** that follows does not appear in normal builds. ** ** These routines are used to print out the content of all or part of a ** parse structures such as Select or Expr. Such printouts are useful ** for helping to understand what is happening inside the code generator ** during the execution of complex SELECT statements. ** ** These routine are not called anywhere from within the normal ** code base. Then are intended to be called from within the debugger ** or from temporary "printf" statements inserted for debugging. */ void sqlite3PrintExpr(Expr *p){ if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){ sqlite3DebugPrintf("(%s", p->u.zToken); }else{ sqlite3DebugPrintf("(%d", p->op); } if( p->pLeft ){ sqlite3DebugPrintf(" "); sqlite3PrintExpr(p->pLeft); } if( p->pRight ){ sqlite3DebugPrintf(" "); sqlite3PrintExpr(p->pRight); } sqlite3DebugPrintf(")"); } void sqlite3PrintExprList(ExprList *pList){ int i; for(i=0; inExpr; i++){ sqlite3PrintExpr(pList->a[i].pExpr); if( inExpr-1 ){ sqlite3DebugPrintf(", "); } } } void sqlite3PrintSelect(Select *p, int indent){ sqlite3DebugPrintf("%*sSELECT(%p) ", indent, "", p); sqlite3PrintExprList(p->pEList); sqlite3DebugPrintf("\n"); if( p->pSrc ){ char *zPrefix; int i; zPrefix = "FROM"; for(i=0; ipSrc->nSrc; i++){ struct SrcList_item *pItem = &p->pSrc->a[i]; sqlite3DebugPrintf("%*s ", indent+6, zPrefix); zPrefix = ""; if( pItem->pSelect ){ sqlite3DebugPrintf("(\n"); sqlite3PrintSelect(pItem->pSelect, indent+10); sqlite3DebugPrintf("%*s)", indent+8, ""); }else if( pItem->zName ){ sqlite3DebugPrintf("%s", pItem->zName); } if( pItem->pTab ){ sqlite3DebugPrintf("(table: %s)", pItem->pTab->zName); } if( pItem->zAlias ){ sqlite3DebugPrintf(" AS %s", pItem->zAlias); } if( ipSrc->nSrc-1 ){ sqlite3DebugPrintf(","); } sqlite3DebugPrintf("\n"); } } if( p->pWhere ){ sqlite3DebugPrintf("%*s WHERE ", indent, ""); sqlite3PrintExpr(p->pWhere); sqlite3DebugPrintf("\n"); } if( p->pGroupBy ){ sqlite3DebugPrintf("%*s GROUP BY ", indent, ""); sqlite3PrintExprList(p->pGroupBy); sqlite3DebugPrintf("\n"); } if( p->pHaving ){ sqlite3DebugPrintf("%*s HAVING ", indent, ""); sqlite3PrintExpr(p->pHaving); sqlite3DebugPrintf("\n"); } if( p->pOrderBy ){ sqlite3DebugPrintf("%*s ORDER BY ", indent, ""); sqlite3PrintExprList(p->pOrderBy); sqlite3DebugPrintf("\n"); } } /* End of the structure debug printing code *****************************************************************************/ #endif /* defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */