Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.0.4
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None
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None
Description
SET optimizer_switch = 'outer_join_with_cache=on'; |
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CREATE TABLE t1 (c1 VARCHAR(6)) ENGINE=MyISAM; |
INSERT INTO t1 VALUES ('s'),('t'); |
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CREATE TABLE t2 (c2 VARCHAR(1)) ENGINE=MyISAM; |
INSERT INTO t2 VALUES ('a'),('x'); |
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SET join_cache_level = 1; |
SELECT t2.* FROM t1 RIGHT JOIN t2 ON c1 = c2 HAVING c2 > 'a' ORDER BY c2 LIMIT 1; |
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SET join_cache_level = 0; |
SELECT t2.* FROM t1 RIGHT JOIN t2 ON c1 = c2 HAVING c2 > 'a' ORDER BY c2 LIMIT 1; |
Result:
SET join_cache_level = 1;
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SELECT t2.* FROM t1 RIGHT JOIN t2 ON c1 = c2 HAVING c2 > 'a' ORDER BY c2 LIMIT 1;
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c2
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SET join_cache_level = 0;
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SELECT t2.* FROM t1 RIGHT JOIN t2 ON c1 = c2 HAVING c2 > 'a' ORDER BY c2 LIMIT 1;
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c2
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x
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The 2nd result is the correct one.
The failure happens on current 10.0-base (revno 3733) and 10.0 (revno 3856). I found the revision on 10.0-base when it started happening, it was a merge from 5.5:
revno: 3645 [merge]
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revision-id: sergii@pisem.net-20130606155128-5mytep9v42626tfs
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committer: Sergei Golubchik <sergii@pisem.net>
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branch nick: 10.0-base
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timestamp: Thu 2013-06-06 17:51:28 +0200
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message:
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5.5 merge
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But on some reason I could not reproduce it on 5.5, even after rolling back to the revision which was merged into 10.0-base.
Attachments
Activity
The bug happens because sort_table_cond is extracted incorrectly due to the fact that curr_join->tmp_having needs an update of used tables.
The bug can be fixed with the following patch:
=== modified file 'sql/sql_select.cc'
— sql/sql_select.cc 2013-10-17 05:45:31 +0000
+++ sql/sql_select.cc 2013-10-21 22:23:16 +0000
@@ -2903,6 +2903,7 @@ void JOIN::exec_inner()
JOIN_TAB *curr_table= &curr_join->join_tab[curr_join->const_tables];
table_map used_tables= (curr_join->const_table_map |
curr_table->table->map);
+ curr_join->tmp_having->update_used_tables();
Item* sort_table_cond= make_cond_for_table(thd, curr_join->tmp_having,
used_tables,
It looks like the bug can manifest itself only starting with10.0-base.
The bug is reproducible with a regular join as well:
MariaDB [test]> INSERT INTO t1 values ('a'), ('x');
Query OK, 2 rows affected (0.00 sec)
MariaDB [test]> SELECT * FROM t1 JOIN t2 ON c1 = c2 HAVING c2 > 'a' ORDER BY c2 LIMIT 1;
Empty set (0.00 sec)
MariaDB [test]> SET join_cache_level = 0;
Query OK, 0 rows affected (0.00 sec)
MariaDB [test]> SELECT * FROM t1 JOIN t2 ON c1 = c2 HAVING c2 > 'a' ORDER BY c2 LIMIT 1;
-----
-----+-----
-----+-----
-----+1 row in set (0.00 sec)