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Overview
Comment:Reduce the memory required by prepared statements that use the IN operator with a list on the right and an INTEGER PRIMARY KEY on the left.
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SHA1:e7984ad2f7e4be30e7198ebd6609a7f6177513e2
User & Date: drh 2009-10-29 13:48:11
Context
2009-10-30
13:25
Avoid storing the result register for EXISTS and SELECT in any field of the Expr object - simply return the register number as the return value of the function that codes those expressions. check-in: 7253f8fa user: drh tags: trunk
2009-10-29
13:48
Reduce the memory required by prepared statements that use the IN operator with a list on the right and an INTEGER PRIMARY KEY on the left. check-in: e7984ad2 user: drh tags: trunk
2009-10-27
18:06
Minor updates and corrections to comments in btreeInt.h. No changes to code. check-in: ad949fa1 user: drh tags: trunk
Changes
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Changes to src/expr.c.

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        /* Loop through each expression in <exprlist>. */
        r1 = sqlite3GetTempReg(pParse);
        r2 = sqlite3GetTempReg(pParse);
        sqlite3VdbeAddOp2(v, OP_Null, 0, r2);
        for(i=pList->nExpr, pItem=pList->a; i>0; i--, pItem++){
          Expr *pE2 = pItem->pExpr;


          /* If the expression is not constant then we will need to
          ** disable the test that was generated above that makes sure
          ** this code only executes once.  Because for a non-constant
          ** expression we need to rerun this code each time.
          */
          if( testAddr && !sqlite3ExprIsConstant(pE2) ){
            sqlite3VdbeChangeToNoop(v, testAddr-1, 2);
            testAddr = 0;
          }

          /* Evaluate the expression and insert it into the temp table */



          r3 = sqlite3ExprCodeTarget(pParse, pE2, r1);
          if( isRowid ){
            sqlite3VdbeAddOp2(v, OP_MustBeInt, r3, sqlite3VdbeCurrentAddr(v)+2);

            sqlite3VdbeAddOp3(v, OP_Insert, pExpr->iTable, r2, r3);
          }else{
            sqlite3VdbeAddOp4(v, OP_MakeRecord, r3, 1, r2, &affinity, 1);
            sqlite3ExprCacheAffinityChange(pParse, r3, 1);
            sqlite3VdbeAddOp2(v, OP_IdxInsert, pExpr->iTable, r2);

          }
        }
        sqlite3ReleaseTempReg(pParse, r1);
        sqlite3ReleaseTempReg(pParse, r2);
      }
      if( !isRowid ){
        sqlite3VdbeChangeP4(v, addr, (void *)&keyInfo, P4_KEYINFO);
................................................................................
** factoring out of a loop, then evaluate the expression
** into a register and convert the expression into a TK_REGISTER
** expression.
*/
static int evalConstExpr(Walker *pWalker, Expr *pExpr){
  Parse *pParse = pWalker->pParse;
  switch( pExpr->op ){

    case TK_REGISTER: {
      return WRC_Prune;
    }
    case TK_FUNCTION:
    case TK_AGG_FUNCTION:
    case TK_CONST_FUNC: {
      /* The arguments to a function have a fixed destination.







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        /* Loop through each expression in <exprlist>. */
        r1 = sqlite3GetTempReg(pParse);
        r2 = sqlite3GetTempReg(pParse);
        sqlite3VdbeAddOp2(v, OP_Null, 0, r2);
        for(i=pList->nExpr, pItem=pList->a; i>0; i--, pItem++){
          Expr *pE2 = pItem->pExpr;
          int iValToIns;

          /* If the expression is not constant then we will need to
          ** disable the test that was generated above that makes sure
          ** this code only executes once.  Because for a non-constant
          ** expression we need to rerun this code each time.
          */
          if( testAddr && !sqlite3ExprIsConstant(pE2) ){
            sqlite3VdbeChangeToNoop(v, testAddr-1, 2);
            testAddr = 0;
          }

          /* Evaluate the expression and insert it into the temp table */
          if( isRowid && sqlite3ExprIsInteger(pE2, &iValToIns) ){
            sqlite3VdbeAddOp3(v, OP_InsertInt, pExpr->iTable, r2, iValToIns);
          }else{
            r3 = sqlite3ExprCodeTarget(pParse, pE2, r1);
            if( isRowid ){
              sqlite3VdbeAddOp2(v, OP_MustBeInt, r3,
                                sqlite3VdbeCurrentAddr(v)+2);
              sqlite3VdbeAddOp3(v, OP_Insert, pExpr->iTable, r2, r3);
            }else{
              sqlite3VdbeAddOp4(v, OP_MakeRecord, r3, 1, r2, &affinity, 1);
              sqlite3ExprCacheAffinityChange(pParse, r3, 1);
              sqlite3VdbeAddOp2(v, OP_IdxInsert, pExpr->iTable, r2);
            }
          }
        }
        sqlite3ReleaseTempReg(pParse, r1);
        sqlite3ReleaseTempReg(pParse, r2);
      }
      if( !isRowid ){
        sqlite3VdbeChangeP4(v, addr, (void *)&keyInfo, P4_KEYINFO);
................................................................................
** factoring out of a loop, then evaluate the expression
** into a register and convert the expression into a TK_REGISTER
** expression.
*/
static int evalConstExpr(Walker *pWalker, Expr *pExpr){
  Parse *pParse = pWalker->pParse;
  switch( pExpr->op ){
    case TK_IN:
    case TK_REGISTER: {
      return WRC_Prune;
    }
    case TK_FUNCTION:
    case TK_AGG_FUNCTION:
    case TK_CONST_FUNC: {
      /* The arguments to a function have a fixed destination.

Changes to src/vdbe.c.

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** and register P2 becomes ephemeral.  If the cursor is changed, the
** value of register P2 will then change.  Make sure this does not
** cause any problems.)
**
** This instruction only works on tables.  The equivalent instruction
** for indices is OP_IdxInsert.
*/





case OP_Insert: {

  Mem *pData;       /* MEM cell holding data for the record to be inserted */
  Mem *pKey;        /* MEM cell holding key  for the record */
  i64 iKey;         /* The integer ROWID or key for the record to be inserted */
  VdbeCursor *pC;   /* Cursor to table into which insert is written */
  int nZero;        /* Number of zero-bytes to append */
  int seekResult;   /* Result of prior seek or 0 if no USESEEKRESULT flag */
  const char *zDb;  /* database name - used by the update hook */
  const char *zTbl; /* Table name - used by the opdate hook */
  int op;           /* Opcode for update hook: SQLITE_UPDATE or SQLITE_INSERT */

  pData = &p->aMem[pOp->p2];
  pKey = &p->aMem[pOp->p3];
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->pCursor!=0 );
  assert( pC->pseudoTableReg==0 );
  assert( pKey->flags & MEM_Int );
  assert( pC->isTable );
  REGISTER_TRACE(pOp->p2, pData);
  REGISTER_TRACE(pOp->p3, pKey);





  iKey = pKey->u.i;





  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = pKey->u.i;
  if( pData->flags & MEM_Null ){
    pData->z = 0;
    pData->n = 0;
  }else{
    assert( pData->flags & (MEM_Blob|MEM_Str) );
  }
  seekResult = ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0);







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** and register P2 becomes ephemeral.  If the cursor is changed, the
** value of register P2 will then change.  Make sure this does not
** cause any problems.)
**
** This instruction only works on tables.  The equivalent instruction
** for indices is OP_IdxInsert.
*/
/* Opcode: InsertInt P1 P2 P3 P4 P5
**
** This works exactly like OP_Insert except that the key is the
** integer value P3, not the value of the integer stored in register P3.
*/
case OP_Insert: 
case OP_InsertInt: {
  Mem *pData;       /* MEM cell holding data for the record to be inserted */
  Mem *pKey;        /* MEM cell holding key  for the record */
  i64 iKey;         /* The integer ROWID or key for the record to be inserted */
  VdbeCursor *pC;   /* Cursor to table into which insert is written */
  int nZero;        /* Number of zero-bytes to append */
  int seekResult;   /* Result of prior seek or 0 if no USESEEKRESULT flag */
  const char *zDb;  /* database name - used by the update hook */
  const char *zTbl; /* Table name - used by the opdate hook */
  int op;           /* Opcode for update hook: SQLITE_UPDATE or SQLITE_INSERT */

  pData = &p->aMem[pOp->p2];

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->pCursor!=0 );
  assert( pC->pseudoTableReg==0 );

  assert( pC->isTable );
  REGISTER_TRACE(pOp->p2, pData);


  if( pOp->opcode==OP_Insert ){
    pKey = &p->aMem[pOp->p3];
    assert( pKey->flags & MEM_Int );
    REGISTER_TRACE(pOp->p3, pKey);
    iKey = pKey->u.i;
  }else{
    assert( pOp->opcode==OP_InsertInt );
    iKey = pOp->p3;
  }

  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = iKey;
  if( pData->flags & MEM_Null ){
    pData->z = 0;
    pData->n = 0;
  }else{
    assert( pData->flags & (MEM_Blob|MEM_Str) );
  }
  seekResult = ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0);