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Overview
Comment:Avoid unnecessary calls to sqlite3VarintLen() from the OP_MakeRecord opcode.
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SHA1:7a234fc3c5e7970ffe0b8d6ac33c26acb64b5c4d
User & Date: drh 2013-12-08 22:59:29
Context
2013-12-08
23:33
Another simplification to the OP_MakeRecord opcode, making it slightly faster and very slightly smaller. check-in: f2f5a3ce user: drh tags: trunk
22:59
Avoid unnecessary calls to sqlite3VarintLen() from the OP_MakeRecord opcode. check-in: 7a234fc3 user: drh tags: trunk
19:54
Interchange two conditions in an "if" statment in sqlite3PagerAcquire() for very slight (0.06%) overall performance increase. check-in: fbcc1a3e user: drh tags: trunk
Changes
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Changes to src/vdbe.c.

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    }
    if( pRec->flags&MEM_Zero && pRec->n>0 ){
      sqlite3VdbeMemExpandBlob(pRec);
    }
    serial_type = sqlite3VdbeSerialType(pRec, file_format);
    len = sqlite3VdbeSerialTypeLen(serial_type);
    nData += len;
    nHdr += sqlite3VarintLen(serial_type);
    if( pRec->flags & MEM_Zero ){
      /* Only pure zero-filled BLOBs can be input to this Opcode.
      ** We do not allow blobs with a prefix and a zero-filled tail. */
      nZero += pRec->u.nZero;
    }else if( len ){
      nZero = 0;
    }
  }

  /* Add the initial header varint and total the size */





  nHdr += nVarint = sqlite3VarintLen(nHdr);

  if( nVarint<sqlite3VarintLen(nHdr) ){
    nHdr++;
  }
  nByte = nHdr+nData-nZero;
  if( nByte>db->aLimit[SQLITE_LIMIT_LENGTH] ){
    goto too_big;
  }

  /* Make sure the output register has a buffer large enough to store 







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    }
    if( pRec->flags&MEM_Zero && pRec->n>0 ){
      sqlite3VdbeMemExpandBlob(pRec);
    }
    serial_type = sqlite3VdbeSerialType(pRec, file_format);
    len = sqlite3VdbeSerialTypeLen(serial_type);
    nData += len;
    nHdr += serial_type<=127 ? 1 : sqlite3VarintLen(serial_type);
    if( pRec->flags & MEM_Zero ){
      /* Only pure zero-filled BLOBs can be input to this Opcode.
      ** We do not allow blobs with a prefix and a zero-filled tail. */
      nZero += pRec->u.nZero;
    }else if( len ){
      nZero = 0;
    }
  }

  /* Add the initial header varint and total the size */
  if( nHdr<=126 ){
    /* The common case */
    nHdr += 1;
  }else{
    /* Rare case of a really large header */
    nVarint = sqlite3VarintLen(nHdr);
    nHdr += nVarint;
    if( nVarint<sqlite3VarintLen(nHdr) ) nHdr++;

  }
  nByte = nHdr+nData-nZero;
  if( nByte>db->aLimit[SQLITE_LIMIT_LENGTH] ){
    goto too_big;
  }

  /* Make sure the output register has a buffer large enough to store