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Overview
Comment:Get LIMIT and OFFSET working again for negative limits and offsets. Ticket #1586. (CVS 2889)
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: b2ac0be07ec76ab23b7e5b800c0bc62d0bc97f4b
User & Date: drh 2006-01-08 18:10:18.000
Context
2006-01-09
00:09
Remove benign reference to an uninitialized variable. Ticket #1590. (CVS 2890) (check-in: 32998fe8ed user: drh tags: trunk)
2006-01-08
18:10
Get LIMIT and OFFSET working again for negative limits and offsets. Ticket #1586. (CVS 2889) (check-in: b2ac0be07e user: drh tags: trunk)
05:26
Remove some cruft from the VDBE. Bring comments up to date. (CVS 2888) (check-in: 41aef6496a user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/analyze.c.
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/*
** 2005 July 8
**
** 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 code associated with the ANALYZE command.
**
** @(#) $Id: analyze.c,v 1.13 2006/01/07 13:21:04 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_ANALYZE
#include "sqliteInt.h"

/*
** This routine generates code that opens the sqlite_stat1 table on cursor
** iStatCur.













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/*
** 2005 July 8
**
** 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 code associated with the ANALYZE command.
**
** @(#) $Id: analyze.c,v 1.14 2006/01/08 18:10:18 drh Exp $
*/
#ifndef SQLITE_OMIT_ANALYZE
#include "sqliteInt.h"

/*
** This routine generates code that opens the sqlite_stat1 table on cursor
** iStatCur.
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    }

    /* Do the analysis.
    */
    endOfLoop = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, endOfLoop);
    topOfLoop = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp(v, OP_MemIncr, iMem, 0);
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+nCol+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Ne, 0x100, 0);
    }
    sqlite3VdbeAddOp(v, OP_Goto, 0, endOfLoop);
    for(i=0; i<nCol; i++){
      addr = sqlite3VdbeAddOp(v, OP_MemIncr, iMem+i+1, 0);
      sqlite3VdbeChangeP2(v, topOfLoop + 3*i + 3, addr);
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, 1);
    }
    sqlite3VdbeResolveLabel(v, endOfLoop);
    sqlite3VdbeAddOp(v, OP_Next, iIdxCur, topOfLoop);
    sqlite3VdbeAddOp(v, OP_Close, iIdxCur, 0);







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    }

    /* Do the analysis.
    */
    endOfLoop = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, endOfLoop);
    topOfLoop = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp(v, OP_MemIncr, 1, iMem);
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+nCol+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Ne, 0x100, 0);
    }
    sqlite3VdbeAddOp(v, OP_Goto, 0, endOfLoop);
    for(i=0; i<nCol; i++){
      addr = sqlite3VdbeAddOp(v, OP_MemIncr, 1, iMem+i+1);
      sqlite3VdbeChangeP2(v, topOfLoop + 3*i + 3, addr);
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, 1);
    }
    sqlite3VdbeResolveLabel(v, endOfLoop);
    sqlite3VdbeAddOp(v, OP_Next, iIdxCur, topOfLoop);
    sqlite3VdbeAddOp(v, OP_Close, iIdxCur, 0);
Changes to src/insert.c.
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**    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 INSERT statements in SQLite.
**
** $Id: insert.c,v 1.153 2006/01/07 13:21:04 danielk1977 Exp $
*/
#include "sqliteInt.h"

/*
** Set P3 of the most recently inserted opcode to a column affinity
** string for index pIdx. A column affinity string has one character
** for each column in the table, according to the affinity of the column:







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**    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 INSERT statements in SQLite.
**
** $Id: insert.c,v 1.154 2006/01/08 18:10:18 drh Exp $
*/
#include "sqliteInt.h"

/*
** Set P3 of the most recently inserted opcode to a column affinity
** string for index pIdx. A column affinity string has one character
** for each column in the table, according to the affinity of the column:
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    sqlite3CompleteInsertion(pParse, pTab, base, 0,0,0,
                            (triggers_exist & TRIGGER_AFTER)!=0 ? newIdx : -1);
  }

  /* Update the count of rows that are inserted
  */
  if( (db->flags & SQLITE_CountRows)!=0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, iCntMem, 0);
  }

  if( triggers_exist ){
    /* Close all tables opened */
    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Close, base, 0);
      for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){







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    sqlite3CompleteInsertion(pParse, pTab, base, 0,0,0,
                            (triggers_exist & TRIGGER_AFTER)!=0 ? newIdx : -1);
  }

  /* Update the count of rows that are inserted
  */
  if( (db->flags & SQLITE_CountRows)!=0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, 1, iCntMem);
  }

  if( triggers_exist ){
    /* Close all tables opened */
    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Close, base, 0);
      for(idx=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, idx++){
Changes to src/pragma.c.
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/*
** 2003 April 6
**
** 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 code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.109 2006/01/06 14:32:20 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/













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/*
** 2003 April 6
**
** 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 code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.110 2006/01/08 18:10:18 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/
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      sqlite3VdbeAddOp(v, OP_Eq, 0, addr+7);
      sqlite3VdbeOp3(v, OP_String8, 0, 0,
         sqlite3MPrintf("*** in database %s ***\n", db->aDb[i].zName),
         P3_DYNAMIC);
      sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
      sqlite3VdbeAddOp(v, OP_Concat, 0, 1);
      sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
      sqlite3VdbeAddOp(v, OP_MemIncr, 0, 0);

      /* Make sure all the indices are constructed correctly.
      */
      sqlite3CodeVerifySchema(pParse, i);
      for(x=sqliteHashFirst(pTbls); x; x=sqliteHashNext(x)){
        Table *pTab = sqliteHashData(x);
        Index *pIdx;
        int loopTop;

        if( pTab->pIndex==0 ) continue;
        sqlite3OpenTableAndIndices(pParse, pTab, 1, OP_OpenRead);
        sqlite3VdbeAddOp(v, OP_MemInt, 0, 1);
        loopTop = sqlite3VdbeAddOp(v, OP_Rewind, 1, 0);
        sqlite3VdbeAddOp(v, OP_MemIncr, 1, 0);
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
          int jmp2;
          static const VdbeOpList idxErr[] = {
            { OP_MemIncr,     0,  0,  0},
            { OP_String8,     0,  0,  "rowid "},
            { OP_Rowid,       1,  0,  0},
            { OP_String8,     0,  0,  " missing from index "},
            { OP_String8,     0,  0,  0},    /* 4 */
            { OP_Concat,      2,  0,  0},
            { OP_Callback,    1,  0,  0},
          };
          sqlite3GenerateIndexKey(v, pIdx, 1);
          jmp2 = sqlite3VdbeAddOp(v, OP_Found, j+2, 0);
          addr = sqlite3VdbeAddOpList(v, ArraySize(idxErr), idxErr);
          sqlite3VdbeChangeP3(v, addr+4, pIdx->zName, P3_STATIC);
          sqlite3VdbeJumpHere(v, jmp2);
        }
        sqlite3VdbeAddOp(v, OP_Next, 1, loopTop+1);
        sqlite3VdbeJumpHere(v, loopTop);
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
          static const VdbeOpList cntIdx[] = {
             { OP_MemInt,       0,  2,  0},
             { OP_Rewind,       0,  0,  0},  /* 1 */
             { OP_MemIncr,      2,  0,  0},
             { OP_Next,         0,  0,  0},  /* 3 */
             { OP_MemLoad,      1,  0,  0},
             { OP_MemLoad,      2,  0,  0},
             { OP_Eq,           0,  0,  0},  /* 6 */
             { OP_MemIncr,      0,  0,  0},
             { OP_String8,      0,  0,  "wrong # of entries in index "},
             { OP_String8,      0,  0,  0},  /* 9 */
             { OP_Concat,       0,  0,  0},
             { OP_Callback,     1,  0,  0},
          };
          if( pIdx->tnum==0 ) continue;
          addr = sqlite3VdbeAddOpList(v, ArraySize(cntIdx), cntIdx);







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      sqlite3VdbeAddOp(v, OP_Eq, 0, addr+7);
      sqlite3VdbeOp3(v, OP_String8, 0, 0,
         sqlite3MPrintf("*** in database %s ***\n", db->aDb[i].zName),
         P3_DYNAMIC);
      sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
      sqlite3VdbeAddOp(v, OP_Concat, 0, 1);
      sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
      sqlite3VdbeAddOp(v, OP_MemIncr, 1, 0);

      /* Make sure all the indices are constructed correctly.
      */
      sqlite3CodeVerifySchema(pParse, i);
      for(x=sqliteHashFirst(pTbls); x; x=sqliteHashNext(x)){
        Table *pTab = sqliteHashData(x);
        Index *pIdx;
        int loopTop;

        if( pTab->pIndex==0 ) continue;
        sqlite3OpenTableAndIndices(pParse, pTab, 1, OP_OpenRead);
        sqlite3VdbeAddOp(v, OP_MemInt, 0, 1);
        loopTop = sqlite3VdbeAddOp(v, OP_Rewind, 1, 0);
        sqlite3VdbeAddOp(v, OP_MemIncr, 1, 1);
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
          int jmp2;
          static const VdbeOpList idxErr[] = {
            { OP_MemIncr,     1,  0,  0},
            { OP_String8,     0,  0,  "rowid "},
            { OP_Rowid,       1,  0,  0},
            { OP_String8,     0,  0,  " missing from index "},
            { OP_String8,     0,  0,  0},    /* 4 */
            { OP_Concat,      2,  0,  0},
            { OP_Callback,    1,  0,  0},
          };
          sqlite3GenerateIndexKey(v, pIdx, 1);
          jmp2 = sqlite3VdbeAddOp(v, OP_Found, j+2, 0);
          addr = sqlite3VdbeAddOpList(v, ArraySize(idxErr), idxErr);
          sqlite3VdbeChangeP3(v, addr+4, pIdx->zName, P3_STATIC);
          sqlite3VdbeJumpHere(v, jmp2);
        }
        sqlite3VdbeAddOp(v, OP_Next, 1, loopTop+1);
        sqlite3VdbeJumpHere(v, loopTop);
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
          static const VdbeOpList cntIdx[] = {
             { OP_MemInt,       0,  2,  0},
             { OP_Rewind,       0,  0,  0},  /* 1 */
             { OP_MemIncr,      1,  2,  0},
             { OP_Next,         0,  0,  0},  /* 3 */
             { OP_MemLoad,      1,  0,  0},
             { OP_MemLoad,      2,  0,  0},
             { OP_Eq,           0,  0,  0},  /* 6 */
             { OP_MemIncr,      1,  0,  0},
             { OP_String8,      0,  0,  "wrong # of entries in index "},
             { OP_String8,      0,  0,  0},  /* 9 */
             { OP_Concat,       0,  0,  0},
             { OP_Callback,     1,  0,  0},
          };
          if( pIdx->tnum==0 ) continue;
          addr = sqlite3VdbeAddOpList(v, ArraySize(cntIdx), cntIdx);
Changes to src/select.c.
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**    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.
**
** $Id: select.c,v 1.287 2006/01/08 05:02:55 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.







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**    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.
**
** $Id: select.c,v 1.288 2006/01/08 18:10:18 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.
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  Vdbe *v = pParse->pVdbe;
  sqlite3ExprCodeExprList(pParse, pOrderBy);
  sqlite3VdbeAddOp(v, OP_Sequence, pOrderBy->iECursor, 0);
  sqlite3VdbeAddOp(v, OP_Pull, pOrderBy->nExpr + 1, 0);
  sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr + 2, 0);
  sqlite3VdbeAddOp(v, OP_IdxInsert, pOrderBy->iECursor, 0);
  if( pSelect->iLimit>=0 ){
    int addr1;

    sqlite3VdbeAddOp(v, OP_MemIncr, pSelect->iLimit+1, 0);
    addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, pSelect->iLimit+1, 0);
    sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
    sqlite3VdbeJumpHere(v, addr1);
    sqlite3VdbeAddOp(v, OP_Last, pOrderBy->iECursor, 0);
    sqlite3VdbeAddOp(v, OP_Delete, pOrderBy->iECursor, 0);
    sqlite3VdbeJumpHere(v, addr1+1);
    pSelect->iLimit = -1;
  }
}

/*
** 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 */
  int nPop          /* Number of times to pop stack when jumping */
){
  if( p->iOffset>=0 && iContinue!=0 ){
    int addr = sqlite3VdbeCurrentAddr(v) + 3;
    if( nPop>0 ) addr++;
    sqlite3VdbeAddOp(v, OP_MemIncr, p->iOffset, 0);
    sqlite3VdbeAddOp(v, OP_IfMemPos, p->iOffset, addr);
    if( nPop>0 ){
      sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
    }
    sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
    VdbeComment((v, "# skip OFFSET records"));

  }
}

/*
** Add code that will check to make sure the top N elements of the
** stack are distinct.  iTab is a sorting index that holds previously
** seen combinations of the N values.  A new entry is made in iTab







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  Vdbe *v = pParse->pVdbe;
  sqlite3ExprCodeExprList(pParse, pOrderBy);
  sqlite3VdbeAddOp(v, OP_Sequence, pOrderBy->iECursor, 0);
  sqlite3VdbeAddOp(v, OP_Pull, pOrderBy->nExpr + 1, 0);
  sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr + 2, 0);
  sqlite3VdbeAddOp(v, OP_IdxInsert, pOrderBy->iECursor, 0);
  if( pSelect->iLimit>=0 ){
    int addr1, addr2;
    addr1 = sqlite3VdbeAddOp(v, OP_IfMemZero, pSelect->iLimit+1, 0);
    sqlite3VdbeAddOp(v, OP_MemIncr, -1, pSelect->iLimit+1);

    addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
    sqlite3VdbeJumpHere(v, addr1);
    sqlite3VdbeAddOp(v, OP_Last, pOrderBy->iECursor, 0);
    sqlite3VdbeAddOp(v, OP_Delete, pOrderBy->iECursor, 0);
    sqlite3VdbeJumpHere(v, addr2);
    pSelect->iLimit = -1;
  }
}

/*
** 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 */
  int nPop          /* Number of times to pop stack when jumping */
){
  if( p->iOffset>=0 && iContinue!=0 ){
    int addr;

    sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iOffset);
    addr = sqlite3VdbeAddOp(v, OP_IfMemNeg, p->iOffset, addr);
    if( nPop>0 ){
      sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
    }
    sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
    VdbeComment((v, "# skip OFFSET records"));
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*
** Add code that will check to make sure the top N elements of the
** stack are distinct.  iTab is a sorting index that holds previously
** seen combinations of the N values.  A new entry is made in iTab
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    }
#endif
  }

  /* Jump to the end of the loop if the LIMIT is reached.
  */
  if( p->iLimit>=0 && pOrderBy==0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, 0);
    sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, iBreak);
  }
  return 0;
}

/*
** Given an expression list, generate a KeyInfo structure that records







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    }
#endif
  }

  /* Jump to the end of the loop if the LIMIT is reached.
  */
  if( p->iLimit>=0 && pOrderBy==0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
    sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, iBreak);
  }
  return 0;
}

/*
** Given an expression list, generate a KeyInfo structure that records
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740
741
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      break;
    }
  }

  /* Jump to the end of the loop when the LIMIT is reached
  */
  if( p->iLimit>=0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, 0);
    sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
  }

  /* The bottom of the loop
  */
  sqlite3VdbeResolveLabel(v, cont);
  sqlite3VdbeAddOp(v, OP_Next, iTab, addr);







|







735
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741
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      break;
    }
  }

  /* Jump to the end of the loop when the LIMIT is reached
  */
  if( p->iLimit>=0 ){
    sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
    sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
  }

  /* The bottom of the loop
  */
  sqlite3VdbeResolveLabel(v, cont);
  sqlite3VdbeAddOp(v, OP_Next, iTab, addr);
1360
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1371
1372
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1379
1380
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1382
1383
1384
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1386





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1421
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Vdbe *sqlite3GetVdbe(Parse *pParse){
  Vdbe *v = pParse->pVdbe;
  if( v==0 ){
    v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db);
  }
  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){





  /* 
  ** "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.
  */
  if( p->pLimit ){
    int iMem = pParse->nMem;
    pParse->nMem += 2;
    Vdbe *v = sqlite3GetVdbe(pParse);
    if( v==0 ) return;
    sqlite3ExprCode(pParse, p->pLimit);
    sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
    sqlite3VdbeAddOp(v, OP_Negative, 0, 0);
    sqlite3VdbeAddOp(v, OP_MemStore, iMem, 0);
    VdbeComment((v, "# LIMIT counter"));
    sqlite3VdbeAddOp(v, OP_IfMemZero, iMem, iBreak);
    p->iLimit = iMem;
  }
  if( p->pOffset ){
    int iMem = pParse->nMem++;
    Vdbe *v = sqlite3GetVdbe(pParse);
    if( v==0 ) return;
    sqlite3ExprCode(pParse, p->pOffset);
    sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
    sqlite3VdbeAddOp(v, OP_Negative, 0, 0);
    sqlite3VdbeAddOp(v, OP_MemStore, iMem, p->pLimit==0);
    VdbeComment((v, "# OFFSET counter"));




    if( p->pLimit ){
      sqlite3VdbeAddOp(v, OP_Add, 0, 0);
    }
    p->iOffset = iMem;
  }
  if( p->pLimit ){




    Vdbe *v = pParse->pVdbe;
    sqlite3VdbeAddOp(v, OP_MemStore, p->iLimit+1, 1);
    VdbeComment((v, "# LIMIT+OFFSET"));

  }
}

/*
** Allocate a virtual index to use for sorting.
*/
static void createSortingIndex(Parse *pParse, Select *p, ExprList *pOrderBy){







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>
>



<


>
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>







1360
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1367
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1406
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1409
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1416
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1425
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Vdbe *sqlite3GetVdbe(Parse *pParse){
  Vdbe *v = pParse->pVdbe;
  if( v==0 ){
    v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db);
  }
  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;
  int iLimit;
  int iOffset;
  int addr1, addr2;

  /* 
  ** "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.
  */
  if( p->pLimit ){
    p->iLimit = iLimit = pParse->nMem;
    pParse->nMem += 2;
    v = sqlite3GetVdbe(pParse);
    if( v==0 ) return;
    sqlite3ExprCode(pParse, p->pLimit);
    sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);

    sqlite3VdbeAddOp(v, OP_MemStore, iLimit, 0);
    VdbeComment((v, "# LIMIT counter"));
    sqlite3VdbeAddOp(v, OP_IfMemZero, iLimit, iBreak);

  }
  if( p->pOffset ){
    p->iOffset = iOffset = pParse->nMem++;
    v = sqlite3GetVdbe(pParse);
    if( v==0 ) return;
    sqlite3ExprCode(pParse, p->pOffset);
    sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);

    sqlite3VdbeAddOp(v, OP_MemStore, iOffset, p->pLimit==0);
    VdbeComment((v, "# OFFSET counter"));
    addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iOffset, 0);
    sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
    sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
    sqlite3VdbeJumpHere(v, addr1);
    if( p->pLimit ){
      sqlite3VdbeAddOp(v, OP_Add, 0, 0);
    }

  }
  if( p->pLimit ){
    addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iLimit, 0);
    sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
    sqlite3VdbeAddOp(v, OP_MemInt, -1, iLimit+1);
    addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
    sqlite3VdbeJumpHere(v, addr1);
    sqlite3VdbeAddOp(v, OP_MemStore, iLimit+1, 1);
    VdbeComment((v, "# LIMIT+OFFSET"));
    sqlite3VdbeJumpHere(v, addr2);
  }
}

/*
** Allocate a virtual index to use for sorting.
*/
static void createSortingIndex(Parse *pParse, Select *p, ExprList *pOrderBy){
Changes to src/vdbe.c.
39
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43
44
45
46
47
48
49
50
51
52
53
**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.517 2006/01/08 05:26:41 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*







|







39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.518 2006/01/08 18:10:18 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316



















4317
4318
4319
4320
4321
4322
4323
  if( pMem->i<pTos->i){
    pMem->i = pTos->i;
  }
  break;
}
#endif /* SQLITE_OMIT_AUTOINCREMENT */

/* Opcode: MemIncr P1 * *
**
** Increment the integer valued memory cell P1 by 1.
**
** It is illegal to use this instruction on a memory cell that does
** not contain an integer.  An assertion fault will result if you try.
*/
case OP_MemIncr: {        /* no-push */
  int i = pOp->p1;
  Mem *pMem;
  assert( i>=0 && i<p->nMem );
  pMem = &p->aMem[i];
  assert( pMem->flags==MEM_Int );
  pMem->i++;
  assert( pOp->p2==0 );
  break;
}

/* Opcode: IfMemPos P1 P2 *
**
** If the value of memory cell P1 is 1 or greater, jump to P2.  If
** the memory cell holds an integer of 0 or less.
**
** It is illegal to use this instruction on a memory cell that does
** not contain an integer.  An assertion fault will result if you try.
*/
case OP_IfMemPos: {        /* no-push */
  int i = pOp->p1;
  Mem *pMem;
  assert( i>=0 && i<p->nMem );
  pMem = &p->aMem[i];
  assert( pMem->flags==MEM_Int );
  if( pMem->i>0 ){
     pc = pOp->p2 - 1;
  }
  break;
}




















/* Opcode: IfMemZero P1 P2 *
**
** If the value of memory cell P1 is exactly 0, jump to P2. 
**
** It is illegal to use this instruction on a memory cell that does
** not contain an integer.  An assertion fault will result if you try.







|

|





|




|
<





|
<















>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293

4294
4295
4296
4297
4298
4299

4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
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4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
  if( pMem->i<pTos->i){
    pMem->i = pTos->i;
  }
  break;
}
#endif /* SQLITE_OMIT_AUTOINCREMENT */

/* Opcode: MemIncr P1 P2 *
**
** Increment the integer valued memory cell P2 by the value in P1.
**
** It is illegal to use this instruction on a memory cell that does
** not contain an integer.  An assertion fault will result if you try.
*/
case OP_MemIncr: {        /* no-push */
  int i = pOp->p2;
  Mem *pMem;
  assert( i>=0 && i<p->nMem );
  pMem = &p->aMem[i];
  assert( pMem->flags==MEM_Int );
  pMem->i += pOp->p1;

  break;
}

/* Opcode: IfMemPos P1 P2 *
**
** If the value of memory cell P1 is 1 or greater, jump to P2.

**
** It is illegal to use this instruction on a memory cell that does
** not contain an integer.  An assertion fault will result if you try.
*/
case OP_IfMemPos: {        /* no-push */
  int i = pOp->p1;
  Mem *pMem;
  assert( i>=0 && i<p->nMem );
  pMem = &p->aMem[i];
  assert( pMem->flags==MEM_Int );
  if( pMem->i>0 ){
     pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: IfMemNeg P1 P2 *
**
** If the value of memory cell P1 is less than zero, jump to P2. 
**
** It is illegal to use this instruction on a memory cell that does
** not contain an integer.  An assertion fault will result if you try.
*/
case OP_IfMemNeg: {        /* no-push */
  int i = pOp->p1;
  Mem *pMem;
  assert( i>=0 && i<p->nMem );
  pMem = &p->aMem[i];
  assert( pMem->flags==MEM_Int );
  if( pMem->i<0 ){
     pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: IfMemZero P1 P2 *
**
** If the value of memory cell P1 is exactly 0, jump to P2. 
**
** It is illegal to use this instruction on a memory cell that does
** not contain an integer.  An assertion fault will result if you try.
Changes to test/limit.test.
8
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11
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14
15
16
17
18
19
20
21
22
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the LIMIT ... OFFSET ... clause
#  of SELECT statements.
#
# $Id: limit.test,v 1.25 2005/09/08 10:37:01 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
execsql {







|







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9
10
11
12
13
14
15
16
17
18
19
20
21
22
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the LIMIT ... OFFSET ... clause
#  of SELECT statements.
#
# $Id: limit.test,v 1.26 2006/01/08 18:10:18 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
execsql {
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43
44
45
46












47
48
49
50
51
52
53
do_test limit-1.2.1 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 5}
} {0 1 2 3 4}
do_test limit-1.2.2 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 5 OFFSET 2}
} {2 3 4 5 6}
do_test limit-1.2.3 {












  execsql {SELECT x FROM t1 ORDER BY x LIMIT 2, 5}
} {2 3 4 5 6}
do_test limit-1.3 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 5 OFFSET 5}
} {5 6 7 8 9}
do_test limit-1.4.1 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 50 OFFSET 30}







>
>
>
>
>
>
>
>
>
>
>
>







40
41
42
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44
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46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
do_test limit-1.2.1 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 5}
} {0 1 2 3 4}
do_test limit-1.2.2 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 5 OFFSET 2}
} {2 3 4 5 6}
do_test limit-1.2.3 {
  execsql {SELECT x FROM t1 ORDER BY x+1 LIMIT 5 OFFSET -2}
} {0 1 2 3 4}
do_test limit-1.2.4 {
  execsql {SELECT x FROM t1 ORDER BY x+1 LIMIT 2, -5}
} {2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31}
do_test limit-1.2.5 {
  execsql {SELECT x FROM t1 ORDER BY x+1 LIMIT -2, 5}
} {0 1 2 3 4}
do_test limit-1.2.6 {
  execsql {SELECT x FROM t1 ORDER BY x+1 LIMIT -2, -5}
} {0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31}
do_test limit-1.2.7 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 2, 5}
} {2 3 4 5 6}
do_test limit-1.3 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 5 OFFSET 5}
} {5 6 7 8 9}
do_test limit-1.4.1 {
  execsql {SELECT x FROM t1 ORDER BY x LIMIT 50 OFFSET 30}