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Overview
| Comment: | Skip flattening if subquery has LIMIT and outer query is DISTINCT. Fix for ticket [752e1646fc]. |
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| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
559739998833643f589fa76d83600806 |
| User & Date: | shaneh 2011-02-11 20:52:21.000 |
| Original Comment: | Skip flattening if subquery has LIMIT and outer query is DISTINCT. Fix for ticket 752e1646fc. |
Context
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2011-02-11
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| 22:54 | Add a NEVER() around a test that is believed to always be false. (check-in: f7e2ea33d5 user: drh tags: trunk) | |
| 20:52 | Skip flattening if subquery has LIMIT and outer query is DISTINCT. Fix for ticket [752e1646fc]. (check-in: 5597399988 user: shaneh tags: trunk) | |
| 06:59 | Fix a bug in the new WHERE-clause processing that tries to use an index to resolve IS NOT NULL constraints when SQLITE_ENABLE_STAT2 is defined. The bug could cause memory overruns and segfaults. The bug was new to the code and has not appeared in an official release. Found during structural testing. (check-in: a5c36b9f39 user: drh tags: trunk) | |
Changes
configure became a regular file.
| ︙ | ︙ |
install-sh became a regular file.
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Changes to src/select.c.
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2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 | ** have a WHERE clause. ** ** (20) If the sub-query is a compound select, then it must not use ** an ORDER BY clause. Ticket #3773. We could relax this constraint ** somewhat by saying that the terms of the ORDER BY clause must ** appear as unmodified result columns in the outer query. But ** have other optimizations in mind to deal with that case. ** ** In this routine, the "p" parameter is a pointer to the outer query. ** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query ** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates. ** ** If flattening is not attempted, this routine is a no-op and returns 0. ** If flattening is attempted this routine returns 1. | > > > | 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 | ** have a WHERE clause. ** ** (20) If the sub-query is a compound select, then it must not use ** an ORDER BY clause. Ticket #3773. We could relax this constraint ** somewhat by saying that the terms of the ORDER BY clause must ** appear as unmodified result columns in the outer query. But ** have other optimizations in mind to deal with that case. ** ** (21) The subquery does not use LIMIT or the outer query is not ** DISTINCT. (See ticket [752e1646fc]). ** ** In this routine, the "p" parameter is a pointer to the outer query. ** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query ** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates. ** ** If flattening is not attempted, this routine is a no-op and returns 0. ** If flattening is attempted this routine returns 1. |
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2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 |
return 0; /* Restriction (6) */
}
if( p->pOrderBy && pSub->pOrderBy ){
return 0; /* Restriction (11) */
}
if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */
if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */
/* OBSOLETE COMMENT 1:
** Restriction 3: If the subquery is a join, make sure the subquery is
** not used as the right operand of an outer join. Examples of why this
** is not allowed:
**
** t1 LEFT OUTER JOIN (t2 JOIN t3)
| > > > | 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 |
return 0; /* Restriction (6) */
}
if( p->pOrderBy && pSub->pOrderBy ){
return 0; /* Restriction (11) */
}
if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */
if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */
if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){
return 0; /* Restriction (21) */
}
/* OBSOLETE COMMENT 1:
** Restriction 3: If the subquery is a join, make sure the subquery is
** not used as the right operand of an outer join. Examples of why this
** is not allowed:
**
** t1 LEFT OUTER JOIN (t2 JOIN t3)
|
| ︙ | ︙ |
Added test/tkt-752e1646fc.test.
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 |
# 2010 April 15
#
# The author disclaims copyright to this source code. In place of
# a legal notice, here is a blessing:
#
# May you do good and not evil.
# May you find forgiveness for yourself and forgive others.
# May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests to verify that ticket [752e1646fc] has been
# fixed.
#
set testdir [file dirname $argv0]
source $testdir/tester.tcl
do_test tkt-752e1646fc-1.1 {
execsql {
CREATE TABLE "test" ("letter" VARCHAR(1) PRIMARY KEY, "number" INTEGER NOT NULL);
INSERT INTO "test" ("letter", "number") VALUES('b', 1);
INSERT INTO "test" ("letter", "number") VALUES('a', 2);
INSERT INTO "test" ("letter", "number") VALUES('c', 2);
SELECT DISTINCT "number" FROM (SELECT "letter", "number" FROM "test" ORDER BY "letter", "number" LIMIT 1) AS "test";
}
} {2}
finish_test
|