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Comment:Additional optimizations in sqlite3VdbeRecordCompare().
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SHA1:23ea2b700fd6d28d3b13663d164faba3760c572e
User & Date: drh 2009-11-16 03:13:40
References
2009-11-16
21:28
Back out part of the change in [23ea2b700fd6d28d] since TH3 reveals some problems in OOM situations. check-in: 15d215d6 user: drh tags: trunk
Context
2009-11-16
15:11
Use the sqlite3CtypeMap to improve the speed and reduce the size of the logic in the tokenizer that recognizes identifiers. check-in: 1c9243b0 user: drh tags: trunk
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
Changes
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Changes to src/vdbeaux.c.

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  int rc = 0;
  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  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.







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  int rc = 0;
  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  KeyInfo *pKeyInfo;
  Mem mem1;

  pKeyInfo = pPKey2->pKeyInfo;
  mem1.enc = pKeyInfo->enc;
  mem1.db = 0;
  /* mem1.flags = 0;  // Will be initialized by sqlite3VdbeSerialGet() */
  VVA_ONLY( mem1.zMalloc = 0; ) /* Only needed 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.