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Overview
Comment:Optimizations to the sqlite3VdbeRecordCompare() routine help it to run 12.5% faster for some traces.
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SHA1:74c76f0bf946d184275de478ec72220d76342493
User & Date: drh 2009-11-16 02:14:01
Context
2009-11-16
03:13
Additional optimizations in sqlite3VdbeRecordCompare(). check-in: 23ea2b70 user: drh tags: trunk
02:14
Optimizations to the sqlite3VdbeRecordCompare() routine help it to run 12.5% faster for some traces. check-in: 74c76f0b user: drh tags: trunk
2009-11-14
23:22
Optimizations to the main loop inside sqlite3VdbeExec() to help VDBE byte code run a few percent faster. check-in: d622ac6a user: drh tags: trunk
Changes
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Changes to src/vdbeaux.c.

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  KeyInfo *pKeyInfo;
  Mem mem1;

  pKeyInfo = pPKey2->pKeyInfo;
  mem1.enc = pKeyInfo->enc;
  mem1.db = pKeyInfo->db;
  mem1.flags = 0;









  mem1.u.i = 0;  /* not needed, here to silence compiler warning */
  mem1.zMalloc = 0;
  
  idx1 = getVarint32(aKey1, szHdr1);
  d1 = szHdr1;
  if( pPKey2->flags & UNPACKED_IGNORE_ROWID ){
    szHdr1--;
  }
  nField = pKeyInfo->nField;
................................................................................
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);

    /* Do the comparison
    */
    rc = sqlite3MemCompare(&mem1, &pPKey2->aMem[i],
                           i<nField ? pKeyInfo->aColl[i] : 0);
    if( rc!=0 ){
      break;



















    }
    i++;
  }

  /* No memory allocation is ever used on mem1. */

  if( NEVER(mem1.zMalloc) ) sqlite3VdbeMemRelease(&mem1);

  /* If the PREFIX_SEARCH flag is set and all fields except the final
  ** rowid field were equal, then clear the PREFIX_SEARCH flag and set 
  ** pPKey2->rowid to the value of the rowid field in (pKey1, nKey1).
  ** This is used by the OP_IsUnique opcode.
  */
  if( (pPKey2->flags & UNPACKED_PREFIX_SEARCH) && i==(pPKey2->nField-1) ){
    assert( idx1==szHdr1 && rc );
    assert( mem1.flags & MEM_Int );
    pPKey2->flags &= ~UNPACKED_PREFIX_SEARCH;
    pPKey2->rowid = mem1.u.i;
  }

  if( rc==0 ){
    /* rc==0 here means that one of the keys ran out of fields and
    ** all the fields up to that point were equal. If the UNPACKED_INCRKEY
    ** flag is set, then break the tie by treating key2 as larger.
    ** If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
    ** are considered to be equal.  Otherwise, the longer key is the 
    ** larger.  As it happens, the pPKey2 will always be the longer
    ** if there is a difference.
    */

    if( pPKey2->flags & UNPACKED_INCRKEY ){
      rc = -1;
    }else if( pPKey2->flags & UNPACKED_PREFIX_MATCH ){
      /* Leave rc==0 */
    }else if( idx1<szHdr1 ){
      rc = 1;
    }
  }else if( pKeyInfo->aSortOrder && i<pKeyInfo->nField
               && pKeyInfo->aSortOrder[i] ){
    rc = -rc;
  }

  return rc;
}
 

/*
** pCur points at an index entry created using the OP_MakeRecord opcode.
** Read the rowid (the last field in the record) and store it in *rowid.







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  KeyInfo *pKeyInfo;
  Mem mem1;

  pKeyInfo = pPKey2->pKeyInfo;
  mem1.enc = pKeyInfo->enc;
  mem1.db = pKeyInfo->db;
  mem1.flags = 0;
  VVA_ONLY( mem1.zMalloc = 0; ) /* Only used by assert() statements */

  /* Compilers may complain that mem1.u.i is potentially uninitialized.
  ** We could initialize it, as shown here, to silence those complaints.
  ** But in fact, mem1.u.i will never actually be used initialized, and doing 
  ** the unnecessary initialization has a measurable negative performance
  ** impact, since this routine is a very high runner.  And so, we choose
  ** to ignore the compiler warnings and leave this variable uninitialized.
  */
  /*  mem1.u.i = 0;  // not needed, here to silence compiler warning */

  
  idx1 = getVarint32(aKey1, szHdr1);
  d1 = szHdr1;
  if( pPKey2->flags & UNPACKED_IGNORE_ROWID ){
    szHdr1--;
  }
  nField = pKeyInfo->nField;
................................................................................
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);

    /* Do the comparison
    */
    rc = sqlite3MemCompare(&mem1, &pPKey2->aMem[i],
                           i<nField ? pKeyInfo->aColl[i] : 0);
    if( rc!=0 ){
      assert( mem1.zMalloc==0 );  /* See comment below */

      /* Invert the result if we are using DESC sort order. */
      if( pKeyInfo->aSortOrder && i<nField && pKeyInfo->aSortOrder[i] ){
        rc = -rc;
      }
    
      /* If the PREFIX_SEARCH flag is set and all fields except the final
      ** rowid field were equal, then clear the PREFIX_SEARCH flag and set 
      ** pPKey2->rowid to the value of the rowid field in (pKey1, nKey1).
      ** This is used by the OP_IsUnique opcode.
      */
      if( (pPKey2->flags & UNPACKED_PREFIX_SEARCH) && i==(pPKey2->nField-1) ){
        assert( idx1==szHdr1 && rc );
        assert( mem1.flags & MEM_Int );
        pPKey2->flags &= ~UNPACKED_PREFIX_SEARCH;
        pPKey2->rowid = mem1.u.i;
      }
    
      return rc;
    }
    i++;
  }

  /* No memory allocation is ever used on mem1.  Prove this using
  ** the following assert().  If the assert() fails, it indicates a
  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).





  */


  assert( mem1.zMalloc==0 );





  /* rc==0 here means that one of the keys ran out of fields and
  ** all the fields up to that point were equal. If the UNPACKED_INCRKEY
  ** flag is set, then break the tie by treating key2 as larger.
  ** If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
  ** are considered to be equal.  Otherwise, the longer key is the 
  ** larger.  As it happens, the pPKey2 will always be the longer
  ** if there is a difference.
  */
  assert( rc==0 );
  if( pPKey2->flags & UNPACKED_INCRKEY ){
    rc = -1;
  }else if( pPKey2->flags & UNPACKED_PREFIX_MATCH ){
    /* Leave rc==0 */
  }else if( idx1<szHdr1 ){
    rc = 1;
  }





  return rc;
}
 

/*
** pCur points at an index entry created using the OP_MakeRecord opcode.
** Read the rowid (the last field in the record) and store it in *rowid.