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Overview
Comment:Optimization to the OP_MakeRecord opcode makes speed-check.sh run about 1.1 million cycles faster, and results in a slightly smaller library.
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SHA3-256: d10e63629183f6daf0c263cd4dae052a3786c8c1480b3b6a73124b3315e41951
User & Date: drh 2018-09-21 13:07:14
Context
2018-09-21
18:43
Put a limit counter on the query planner that restricts the number of index+constraint options that can be considered for each table in a join. This prevents certain pathological queries from taking up too much time in the query planner. check-in: 8690b5a0cc user: drh tags: trunk
13:07
Optimization to the OP_MakeRecord opcode makes speed-check.sh run about 1.1 million cycles faster, and results in a slightly smaller library. check-in: d10e636291 user: drh tags: trunk
2018-09-20
20:43
Minor code simplification. check-in: 22ae8a52dd user: drh tags: trunk
Changes
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Changes to src/vdbe.c.

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  }else{
    /* Rare case of a really large header */
    nVarint = sqlite3VarintLen(nHdr);
    nHdr += nVarint;
    if( nVarint<sqlite3VarintLen(nHdr) ) nHdr++;
  }
  nByte = nHdr+nData;
  if( nByte+nZero>db->aLimit[SQLITE_LIMIT_LENGTH] ){
    goto too_big;
  }

  /* Make sure the output register has a buffer large enough to store 
  ** the new record. The output register (pOp->p3) is not allowed to
  ** be one of the input registers (because the following call to
  ** sqlite3VdbeMemClearAndResize() could clobber the value before it is used).
  */










  if( sqlite3VdbeMemClearAndResize(pOut, (int)nByte) ){
    goto no_mem;

  }
  zNewRecord = (u8 *)pOut->z;

  /* Write the record */
  i = putVarint32(zNewRecord, nHdr);
  j = nHdr;
  assert( pData0<=pLast );







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  }else{
    /* Rare case of a really large header */
    nVarint = sqlite3VarintLen(nHdr);
    nHdr += nVarint;
    if( nVarint<sqlite3VarintLen(nHdr) ) nHdr++;
  }
  nByte = nHdr+nData;




  /* Make sure the output register has a buffer large enough to store 
  ** the new record. The output register (pOp->p3) is not allowed to
  ** be one of the input registers (because the following call to
  ** sqlite3VdbeMemClearAndResize() could clobber the value before it is used).
  */
  if( nByte+nZero<=pOut->szMalloc ){
    /* The output register is already large enough to hold the record.
    ** No error checks or buffer enlargement is required */
    pOut->z = pOut->zMalloc;
  }else{
    /* Need to make sure that the output is not too big and then enlarge
    ** the output register to hold the full result */
    if( nByte+nZero>db->aLimit[SQLITE_LIMIT_LENGTH] ){
      goto too_big;
    }
    if( sqlite3VdbeMemClearAndResize(pOut, (int)nByte) ){
      goto no_mem;
    }
  }
  zNewRecord = (u8 *)pOut->z;

  /* Write the record */
  i = putVarint32(zNewRecord, nHdr);
  j = nHdr;
  assert( pData0<=pLast );