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Changes In Branch increased-sorting-cost Excluding Merge-Ins
This is equivalent to a diff from 218b2bbb0d to 662e8ccf7e
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2017-02-17
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| 23:52 | Fix the #endif location for an #ifndef SQLITE_UNTESTABLE macro in the command-line shell. (check-in: 8cc9d74c17 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: 85026c8ee1 user: drh tags: auto-analyze) | |
| 02:07 | Merge fixes from trunk. (Leaf check-in: 662e8ccf7e 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: 218b2bbb0d 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: 8a03be1dc4 user: drh tags: trunk) | |
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2017-02-16
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| 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: aa0703e5ce 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;
/* 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);
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