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author | Vicențiu Ciorbaru <cvicentiu@gmail.com> | 2023-02-15 16:20:25 +0200 |
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committer | Vicențiu Ciorbaru <cvicentiu@gmail.com> | 2023-02-15 16:58:31 +0200 |
commit | 4afa3b64c4e5ca12d755124befc373e0f35ff1e1 (patch) | |
tree | a5a8e853662f9120a694ee1f0a5e2ae9425e74e4 /mysql-test/main | |
parent | d2b773d913cdcd35a727643bc16927527a5ee4bc (diff) | |
download | mariadb-git-4afa3b64c4e5ca12d755124befc373e0f35ff1e1.tar.gz |
MDEV-30324: Wrong result upon SELECT DISTINCT ... WITH TIES
WITH TIES would not take effect if SELECT DISTINCT was used in a
context where an INDEX is used to resolve the ORDER BY clause.
WITH TIES relies on the `JOIN::order` to contain the non-constant
fields to test the equality of ORDER BY fiels required for WITH TIES.
The cause of the problem was a premature removal of the `JOIN::order`
member during a DISTINCT optimization. This lead to WITH TIES code assuming
ORDER BY only contained "constant" elements.
Disable this optimization when WITH TIES is in effect.
(side-note: the order by removal does not impact any current tests, thus
it will be removed in a future version)
Reviewed by: monty@mariadb.org
Diffstat (limited to 'mysql-test/main')
-rw-r--r-- | mysql-test/main/fetch_first.result | 28 | ||||
-rw-r--r-- | mysql-test/main/fetch_first.test | 19 |
2 files changed, 47 insertions, 0 deletions
diff --git a/mysql-test/main/fetch_first.result b/mysql-test/main/fetch_first.result index 69a0336d722..df182381d1c 100644 --- a/mysql-test/main/fetch_first.result +++ b/mysql-test/main/fetch_first.result @@ -1378,3 +1378,31 @@ a bar foo DROP TABLE t; +# +# MDEV-30324: Wrong result upon SELECT DISTINCT .. WITH TIES using index +# +CREATE TABLE t1 (a int, b char(3), KEY (a)); +INSERT INTO t1 VALUES (2,'foo'),(3,'bar'),(3,'bar'),(3,'zzz'); +EXPLAIN SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 1 ROWS WITH TIES; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 index NULL a 5 NULL 1 Using temporary +SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 1 ROWS WITH TIES; +a b +2 foo +EXPLAIN SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 2 ROWS WITH TIES; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 index NULL a 5 NULL 2 Using temporary +SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 2 ROWS WITH TIES; +a b +2 foo +3 bar +3 zzz +EXPLAIN SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 3 ROWS WITH TIES; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using temporary; Using filesort +SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 3 ROWS WITH TIES; +a b +2 foo +3 bar +3 zzz +DROP TABLE t1; diff --git a/mysql-test/main/fetch_first.test b/mysql-test/main/fetch_first.test index 62cdd717f81..98bbf1ca06b 100644 --- a/mysql-test/main/fetch_first.test +++ b/mysql-test/main/fetch_first.test @@ -1059,3 +1059,22 @@ SELECT a FROM t ORDER BY a FETCH FIRST 2 ROWS WITH TIES; # Cleanup DROP TABLE t; + +--echo # +--echo # MDEV-30324: Wrong result upon SELECT DISTINCT .. WITH TIES using index +--echo # +CREATE TABLE t1 (a int, b char(3), KEY (a)); +INSERT INTO t1 VALUES (2,'foo'),(3,'bar'),(3,'bar'),(3,'zzz'); + +EXPLAIN SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 1 ROWS WITH TIES; +--sorted_result +SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 1 ROWS WITH TIES; +EXPLAIN SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 2 ROWS WITH TIES; +--sorted_result +SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 2 ROWS WITH TIES; +EXPLAIN SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 3 ROWS WITH TIES; +--sorted_result +SELECT DISTINCT a, b FROM t1 ORDER BY a FETCH FIRST 3 ROWS WITH TIES; + +# Cleanup +DROP TABLE t1; |