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Disallow the one-pass optimization for DELETE if the WHERE clause contains

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a subquery.  Fix for the problem reported by
[forum:/forumpost/e61252062c9d286d|forum post e61252062c9d286d].  This fix
is more restrictive than necessary.  It could be relaxed if the subquery does
not involve the table that is the subject of the DELETE.

FossilOrigin-Name: 73f0036f045bf37193b6e87ae45b578c5831614c530488257c69666178da3aa5
This commit is contained in:
drh
2023-03-15 17:58:51 +00:00
parent eb5d71ed58
commit ffcad5893a
6 changed files with 35 additions and 14 deletions
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21
test/delete.test
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@ -416,4 +416,25 @@ do_execsql_test delete-11.1 {
} {6 2 12 4 18 6 19 23 20 40}
# 2023-03-15
# https://sqlite.org/forum/forumpost/e61252062c9d286d
#
# When the WHERE clause of a DELETE statement contains a subquery
# which uses the table that is being deleted from and there is a
# short-circuit operator of some kind in the WHERE clause such that
# the subquery might not run right away, then the subquery might
# run after one or more rows have been deleted, which can change
# the result of the subquery, and result in the wrong answer.
#
reset_db
do_execsql_test delete-12.0 {
CREATE TABLE t0(vkey INTEGER, pkey INTEGER,c1 INTEGER);
INSERT INTO t0 VALUES(2,1,-20),(2,2,NULL),(2,3,0),(8,4,95);
DELETE FROM t0 WHERE NOT (
(t0.vkey <= t0.c1) AND
(t0.vkey <> (SELECT vkey FROM t0 ORDER BY vkey LIMIT 1 OFFSET 2))
);
SELECT * FROM t0;
} {8 4 95}
finish_test