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Overview
| Comment: | Fix the query planner so that it once again knows that queries without a FROM clause will never return more than one row and hence do not require sorting. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
9f18b303cd1bc5779d82669884f802c7 |
| User & Date: | drh 2014-06-02 11:26:33.102 |
Context
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2014-06-02
| ||
| 18:24 | Fix a typo in a requirements mark comment in a test script. No changes to code. (check-in: 75ff459b06 user: drh tags: trunk) | |
| 11:26 | Fix the query planner so that it once again knows that queries without a FROM clause will never return more than one row and hence do not require sorting. (check-in: 9f18b303cd user: drh tags: trunk) | |
| 09:39 | Add the "valgrind-nolookaside" permutation to permutations.test. (check-in: 8e8472d9b6 user: dan tags: trunk) | |
Changes
Changes to src/where.c.
| ︙ | ︙ | |||
5293 5294 5295 5296 5297 5298 5299 | pParse = pWInfo->pParse; db = pParse->db; nLoop = pWInfo->nLevel; /* TUNING: For simple queries, only the best path is tracked. ** For 2-way joins, the 5 best paths are followed. ** For joins of 3 or more tables, track the 10 best paths */ | | | 5293 5294 5295 5296 5297 5298 5299 5300 5301 5302 5303 5304 5305 5306 5307 |
pParse = pWInfo->pParse;
db = pParse->db;
nLoop = pWInfo->nLevel;
/* TUNING: For simple queries, only the best path is tracked.
** For 2-way joins, the 5 best paths are followed.
** For joins of 3 or more tables, track the 10 best paths */
mxChoice = (nLoop<=1) ? 1 : (nLoop==2 ? 5 : 10);
assert( nLoop<=pWInfo->pTabList->nSrc );
WHERETRACE(0x002, ("---- begin solver\n"));
/* Allocate and initialize space for aTo and aFrom */
ii = (sizeof(WherePath)+sizeof(WhereLoop*)*nLoop)*mxChoice*2;
pSpace = sqlite3DbMallocRaw(db, ii);
if( pSpace==0 ) return SQLITE_NOMEM;
|
| ︙ | ︙ | |||
5323 5324 5325 5326 5327 5328 5329 |
/* Precompute the cost of sorting the final result set, if the caller
** to sqlite3WhereBegin() was concerned about sorting */
if( pWInfo->pOrderBy==0 || nRowEst==0 ){
aFrom[0].isOrdered = 0;
nOrderBy = 0;
}else{
| | | 5323 5324 5325 5326 5327 5328 5329 5330 5331 5332 5333 5334 5335 5336 5337 |
/* Precompute the cost of sorting the final result set, if the caller
** to sqlite3WhereBegin() was concerned about sorting */
if( pWInfo->pOrderBy==0 || nRowEst==0 ){
aFrom[0].isOrdered = 0;
nOrderBy = 0;
}else{
aFrom[0].isOrdered = nLoop>0 ? -1 : 1;
nOrderBy = pWInfo->pOrderBy->nExpr;
}
/* Compute successively longer WherePaths using the previous generation
** of WherePaths as the basis for the next. Keep track of the mxChoice
** best paths at each generation */
for(iLoop=0; iLoop<nLoop; iLoop++){
|
| ︙ | ︙ |
Changes to test/orderby1.test.
| ︙ | ︙ | |||
448 449 450 451 452 453 454 |
INSERT INTO t41 VALUES(1,1),(3,1);
INSERT INTO t42 VALUES(1,13),(1,15),(3,14),(3,16);
SELECT b, y FROM t41 CROSS JOIN t42 ON x=a ORDER BY b, y;
}
} {1 13 1 14 1 15 1 16}
| > | > > > > > > > > > | 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 |
INSERT INTO t41 VALUES(1,1),(3,1);
INSERT INTO t42 VALUES(1,13),(1,15),(3,14),(3,16);
SELECT b, y FROM t41 CROSS JOIN t42 ON x=a ORDER BY b, y;
}
} {1 13 1 14 1 15 1 16}
# No sorting of queries that omit the FROM clause.
#
do_execsql_test 5.0 {
EXPLAIN QUERY PLAN SELECT 5 ORDER BY 1
} {}
do_execsql_test 5.1 {
EXPLAIN QUERY PLAN SELECT 5 UNION ALL SELECT 3 ORDER BY 1
} {~/B-TREE/}
do_execsql_test 5.2 {
SELECT 5 UNION ALL SELECT 3 ORDER BY 1
} {3 5}
finish_test
|