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Overview
Comment:Small performance increase and size reduction in the OP_Column opcode.
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SHA1:a9498407e646305e7b60115d63e85c642bbd1c3f
User & Date: drh 2016-11-25 17:03:03
Context
2016-11-25
19:18
Refactor the sqlite3BtreeKey() and sqlite3BtreeData() internal interfaces into sqlite3BtreePayload() and sqlite3BtreePayloadChecked(), respectively. This is a continuation of the optimization started by check-in [2d831074cf]. The result is a slightly smaller and faster binary. check-in: 49ebc219 user: drh tags: trunk
17:03
Small performance increase and size reduction in the OP_Column opcode. check-in: a9498407 user: drh tags: trunk
15:47
Performance enhancement to sqlite3_snprintf(). check-in: c53dca7f user: drh tags: trunk
Changes
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Changes to src/vdbe.c.

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  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pC!=0 );
  assert( p2<pC->nField );
  aOffset = pC->aOffset;
  assert( pC->eCurType!=CURTYPE_VTAB );
  assert( pC->eCurType!=CURTYPE_PSEUDO || pC->nullRow );
  assert( pC->eCurType!=CURTYPE_SORTER );
  pCrsr = pC->uc.pCursor;

  if( pC->cacheStatus!=p->cacheCtr ){                /*OPTIMIZATION-IF-FALSE*/
    if( pC->nullRow ){
      if( pC->eCurType==CURTYPE_PSEUDO ){
        assert( pC->uc.pseudoTableReg>0 );
        pReg = &aMem[pC->uc.pseudoTableReg];
        assert( pReg->flags & MEM_Blob );
................................................................................
        pC->payloadSize = pC->szRow = avail = pReg->n;
        pC->aRow = (u8*)pReg->z;
      }else{
        sqlite3VdbeMemSetNull(pDest);
        goto op_column_out;
      }
    }else{

      assert( pC->eCurType==CURTYPE_BTREE );
      assert( pCrsr );
      assert( sqlite3BtreeCursorIsValid(pCrsr) );
      pC->payloadSize = sqlite3BtreePayloadSize(pCrsr);
      pC->aRow = sqlite3BtreePayloadFetch(pCrsr, &avail);
      assert( avail<=65536 );  /* Maximum page size is 64KiB */
      if( pC->payloadSize <= (u32)avail ){
................................................................................
    /* If there is more header available for parsing in the record, try
    ** to extract additional fields up through the p2+1-th field 
    */
    if( pC->iHdrOffset<aOffset[0] ){
      /* Make sure zData points to enough of the record to cover the header. */
      if( pC->aRow==0 ){
        memset(&sMem, 0, sizeof(sMem));
        rc = sqlite3VdbeMemFromBtree(pCrsr, 0, aOffset[0], !pC->isTable, &sMem);

        if( rc!=SQLITE_OK ) goto abort_due_to_error;
        zData = (u8*)sMem.z;
      }else{
        zData = pC->aRow;
      }
  
      /* Fill in pC->aType[i] and aOffset[i] values through the p2-th field. */
................................................................................
      **    2. the length(X) function if X is a blob, and
      **    3. if the content length is zero.
      ** So we might as well use bogus content rather than reading
      ** content from disk. */
      static u8 aZero[8];  /* This is the bogus content */
      sqlite3VdbeSerialGet(aZero, t, pDest);
    }else{
      rc = sqlite3VdbeMemFromBtree(pCrsr, aOffset[p2], len, !pC->isTable,
                                   pDest);
      if( rc!=SQLITE_OK ) goto abort_due_to_error;
      sqlite3VdbeSerialGet((const u8*)pDest->z, t, pDest);
      pDest->flags &= ~MEM_Ephem;
    }
  }

op_column_out:







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  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pC!=0 );
  assert( p2<pC->nField );
  aOffset = pC->aOffset;
  assert( pC->eCurType!=CURTYPE_VTAB );
  assert( pC->eCurType!=CURTYPE_PSEUDO || pC->nullRow );
  assert( pC->eCurType!=CURTYPE_SORTER );


  if( pC->cacheStatus!=p->cacheCtr ){                /*OPTIMIZATION-IF-FALSE*/
    if( pC->nullRow ){
      if( pC->eCurType==CURTYPE_PSEUDO ){
        assert( pC->uc.pseudoTableReg>0 );
        pReg = &aMem[pC->uc.pseudoTableReg];
        assert( pReg->flags & MEM_Blob );
................................................................................
        pC->payloadSize = pC->szRow = avail = pReg->n;
        pC->aRow = (u8*)pReg->z;
      }else{
        sqlite3VdbeMemSetNull(pDest);
        goto op_column_out;
      }
    }else{
      pCrsr = pC->uc.pCursor;
      assert( pC->eCurType==CURTYPE_BTREE );
      assert( pCrsr );
      assert( sqlite3BtreeCursorIsValid(pCrsr) );
      pC->payloadSize = sqlite3BtreePayloadSize(pCrsr);
      pC->aRow = sqlite3BtreePayloadFetch(pCrsr, &avail);
      assert( avail<=65536 );  /* Maximum page size is 64KiB */
      if( pC->payloadSize <= (u32)avail ){
................................................................................
    /* If there is more header available for parsing in the record, try
    ** to extract additional fields up through the p2+1-th field 
    */
    if( pC->iHdrOffset<aOffset[0] ){
      /* Make sure zData points to enough of the record to cover the header. */
      if( pC->aRow==0 ){
        memset(&sMem, 0, sizeof(sMem));
        rc = sqlite3VdbeMemFromBtree(pC->uc.pCursor, 0, aOffset[0],
                                     !pC->isTable, &sMem);
        if( rc!=SQLITE_OK ) goto abort_due_to_error;
        zData = (u8*)sMem.z;
      }else{
        zData = pC->aRow;
      }
  
      /* Fill in pC->aType[i] and aOffset[i] values through the p2-th field. */
................................................................................
      **    2. the length(X) function if X is a blob, and
      **    3. if the content length is zero.
      ** So we might as well use bogus content rather than reading
      ** content from disk. */
      static u8 aZero[8];  /* This is the bogus content */
      sqlite3VdbeSerialGet(aZero, t, pDest);
    }else{
      rc = sqlite3VdbeMemFromBtree(pC->uc.pCursor, aOffset[p2], len,
                                   !pC->isTable, pDest);
      if( rc!=SQLITE_OK ) goto abort_due_to_error;
      sqlite3VdbeSerialGet((const u8*)pDest->z, t, pDest);
      pDest->flags &= ~MEM_Ephem;
    }
  }

op_column_out: