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Changes On Branch increased-sorting-cost
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Changes In Branch increased-sorting-cost Excluding Merge-Ins

This is equivalent to a diff from 218b2bbb to 662e8ccf

2017-02-17
23:52
Fix the #endif location for an #ifndef SQLITE_UNTESTABLE macro in the command-line shell. (check-in: 8cc9d74c user: drh tags: trunk)
13:38
Enhance the Index and Table objects so that they remember if their stats come from the sqlite_stat1 table. Make the "PRAGMA stats" an SQLITE_DEBUG only pragma. Add the flags column to "PRAGMA stats". These are all preliminary steps toward a "PRAGMA analyze_ifneeded;" feature. (check-in: 85026c8e user: drh tags: auto-analyze)
02:07
Merge fixes from trunk. (Leaf check-in: 662e8ccf user: drh tags: increased-sorting-cost)
02:04
Fix a test case that was made to fail by the LIKE optimization enhancement in check-in [158290c0ab] but which went unnoticed because test builds were running with ICU enabled and ICU disables the LIKE optimization. (check-in: 218b2bbb user: drh tags: trunk)
01:43
Enable the ".wheretrace" and ".selecttrace" extensions in the command-line shell when compiled on Windows using DEBUG=3 or higher. Fix a harmless warning in the shell that comes up when compiled this way. (check-in: 8a03be1d user: drh tags: trunk)
2017-02-16
21:29
Increase the estimated cost of sorting when sorting wide results sets, to account for the extra storage space and I/O required for the external sort. (check-in: aa0703e5 user: drh tags: increased-sorting-cost)

Changes to src/where.c.

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  **
  ** The (Y/X) term is implemented using stack variable rScale
  ** below.  */
  LogEst rScale, rSortCost;
  assert( nOrderBy>0 && 66==sqlite3LogEst(100) );
  rScale = sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66;
  rSortCost = nRow + rScale + 16;











  /* Multiple by log(M) where M is the number of output rows.
  ** Use the LIMIT for M if it is smaller */
  if( (pWInfo->wctrlFlags & WHERE_USE_LIMIT)!=0 && pWInfo->iLimit<nRow ){
    nRow = pWInfo->iLimit;
  }
  rSortCost += estLog(nRow);







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  **
  ** The (Y/X) term is implemented using stack variable rScale
  ** below.  */
  LogEst rScale, rSortCost;
  assert( nOrderBy>0 && 66==sqlite3LogEst(100) );
  rScale = sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66;
  rSortCost = nRow + rScale + 16;

  /* For wide sorts (many payload columns) increase the sorting cost
  ** to account for the additional I/O used by the external sorting
  ** algorithm when it flushes PMAs to disk.
  */
  if( pWInfo->pResultSet
   && pWInfo->pResultSet->nExpr>6
  ){
    rSortCost += sqlite3LogEst(pWInfo->pResultSet->nExpr) - 26;
  }

  /* Multiple by log(M) where M is the number of output rows.
  ** Use the LIMIT for M if it is smaller */
  if( (pWInfo->wctrlFlags & WHERE_USE_LIMIT)!=0 && pWInfo->iLimit<nRow ){
    nRow = pWInfo->iLimit;
  }
  rSortCost += estLog(nRow);