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| author | drh <> | 2021-07-16 01:19:19 +0000 |
|---|---|---|
| committer | drh <> | 2021-07-16 01:19:19 +0000 |
| commit | 0fb78f0cca4eedc1f2e68fc7fa3395ab6d46576a (patch) | |
| tree | ac60df55a740dad98a806b97836f970719705c38 /src | |
| parent | bb301231788a7ca2292005ecf8d924dbf122f2d2 (diff) | |
| download | sqlite-0fb78f0cca4eedc1f2e68fc7fa3395ab6d46576a.tar.gz sqlite-0fb78f0cca4eedc1f2e68fc7fa3395ab6d46576a.zip | |
Get the "omit ORDER BY in FROM-clause subqueries" optimization working for the
core test cases.
FossilOrigin-Name: e31c5888659ffd4c6d8b68627123df3bbb84bb010b7766b0a74877bf3ba1e52b
Diffstat (limited to 'src')
| -rw-r--r-- | src/select.c | 14 | ||||
| -rw-r--r-- | src/update.c | 1 |
2 files changed, 12 insertions, 3 deletions
diff --git a/src/select.c b/src/select.c index a6513afca..e0ac9db97 100644 --- a/src/select.c +++ b/src/select.c @@ -6386,7 +6386,8 @@ int sqlite3Select( /* If a FROM-clause subquery has an ORDER BY clause that is not ** really doing anything, then delete it now so that it does not - ** interfere with query flattening. + ** interfere with query flattening. See the discussion at + ** https://sqlite.org/forum/forumpost/2d76f2bcf65d256a ** ** Beware of these cases where the ORDER BY clause may not be safely ** omitted: @@ -6394,13 +6395,20 @@ int sqlite3Select( ** (1) There is also a LIMIT clause ** (2) The subquery was added to help with window-function ** processing - ** (3) The outer query uses an aggregate function other than + ** (3) The subquery is in the FROM clause of an UPDATE + ** (4) The outer query uses an aggregate function other than ** the built-in count(), min(), or max(). + ** (5) The ORDER BY isn't going to accomplish anything because + ** one of: + ** (a) The outer query has a different ORDER BY clause + ** (b) The subquery is part of a join + ** See forum post 062d576715d277c8 */ if( pSub->pOrderBy!=0 + && (p->pOrderBy!=0 || pTabList->nSrc>1) /* Condition (5) */ && pSub->pLimit==0 /* Condition (1) */ && (pSub->selFlags & SF_OrderByReqd)==0 /* Condition (2) */ - && (p->selFlags & SF_OrderByReqd)==0 /* Condition (3) */ + && (p->selFlags & SF_OrderByReqd)==0 /* Condition (3) and (4) */ && OptimizationEnabled(db, SQLITE_OmitOrderBy) ){ SELECTTRACE(0x100,pParse,p, diff --git a/src/update.c b/src/update.c index 45f332bf3..c5a01f896 100644 --- a/src/update.c +++ b/src/update.c @@ -261,6 +261,7 @@ static void updateFromSelect( pSelect = sqlite3SelectNew(pParse, pList, pSrc, pWhere2, pGrp, 0, pOrderBy2, SF_UFSrcCheck|SF_IncludeHidden, pLimit2 ); + if( pSelect ) pSelect->selFlags |= SF_OrderByReqd; sqlite3SelectDestInit(&dest, eDest, iEph); dest.iSDParm2 = (pPk ? pPk->nKeyCol : -1); sqlite3Select(pParse, pSelect, &dest); |