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Comment:The trunk assumes that an open range constraint on an indexed term (col>?) term matches 1/4 of the indexed rows, and that a closed constraint (col BETWEEN ? AND ?) matches 1/64. Change this branch to do the same.
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SHA1: 4047ac75e2a8f0b330255501c42e4f04e5ab500d
User & Date: dan 2014-04-28 19:34:06.281
Context
2014-04-28
20:11
Do not reduce the number of rows scanned at all for "IS NOT NULL" constraints. Fix a bug in calculating the number of rows visited by scans of partial indicies. (check-in: a8ae93f0cf user: dan tags: experimental-costs)
19:34
The trunk assumes that an open range constraint on an indexed term (col>?) term matches 1/4 of the indexed rows, and that a closed constraint (col BETWEEN ? AND ?) matches 1/64. Change this branch to do the same. (check-in: 4047ac75e2 user: dan tags: experimental-costs)
15:11
Update unordered.test to take into account for the fact that SQLite now prefers a full-table scan over a non-covering index scan that visits a large percentage of the table rows. (check-in: 20f468dfbc user: dan tags: experimental-costs)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/where.c.
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#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(pBuilder);
#endif
  assert( pLower || pUpper );
  nNew = whereRangeAdjust(pLower, nOut);
  nNew = whereRangeAdjust(pUpper, nNew);






  nOut -= (pLower!=0) + (pUpper!=0);
  if( nNew<10 ) nNew = 10;
  if( nNew<nOut ) nOut = nNew;
  pLoop->nOut = (LogEst)nOut;
  return rc;
}









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#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(pBuilder);
#endif
  assert( pLower || pUpper );
  nNew = whereRangeAdjust(pLower, nOut);
  nNew = whereRangeAdjust(pUpper, nNew);
  /* TUNING: If there is both an upper and lower limit, assume the range is
  ** reduced by an additional 75%. This means that, by default, an open-ended
  ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the
  ** index. While a closed range (e.g. col BETWEEN ? AND ?) is estimated to
  ** match 1/64 of the index. */ 
  if( pLower && pUpper ) nNew -= 20;
  nOut -= (pLower!=0) + (pUpper!=0);
  if( nNew<10 ) nNew = 10;
  if( nNew<nOut ) nOut = nNew;
  pLoop->nOut = (LogEst)nOut;
  return rc;
}
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