2011-06-16 05:44:21.821201+00:00 https://api.launchpad.net/1.0/bugs/430669 https://api.launchpad.net/1.0/~knielsen https://api.launchpad.net/1.0/maria/+milestone/5.1 https://api.launchpad.net/1.0/bugs/430669/linked_branches https://api.launchpad.net/1.0/bugs/430669/activity https://bugs.launchpad.net/bugs/430669 Kristian Nielsen Sergey Petrunia Maria 5.1 Invalid Wishlist 2009-09-16 11:42:10.943382+00:00 (after push of table elimination): CREATE TABLE t1 (a INT, b INT, c INT); INSERT INTO t1 VALUES (1,1,1), (1,1,1); EXPLAIN EXTENDED SELECT c FROM ( SELECT (SELECT COUNT(a) FROM (SELECT COUNT(b) FROM t1) AS x GROUP BY c ) FROM t1 GROUP BY b ) AS y; ERROR 42S22: Unknown column 'c' in 'field list' SHOW WARNINGS; Level Code Message Note 1276 Field or reference 'test.t1.a' of SELECT #3 was resolved in SELECT #2 Note 1276 Field or reference 'test.t1.c' of SELECT #3 was resolved in SELECT #2 Error 1054 Unknown column 'c' in 'field list' Note 1003 select `c` AS `c` from (select (select count(`test`.`t1`.`a`) AS `COUNT(a)` from (select count(`test`.`t1`.`b`) AS `COUNT(b)` from `test`.`t1`) `x` group by `t1`.`c`) AS `(SELECT COUNT(a) FROM (SELECT COUNT(b) FROM t1) AS x GROUP BY c )` from `test`.`t1` group by `test`.`t1`.`b`) `y` The problem here is this output "group by `t1`.`c`". The column `c` is unknown at that place in the query, so it makes no sense to qualify it with the table name t1. This is related to MySQL Bug#37362 (http://bugs.mysql.com/bug.php?id=37362), from which the test case originates. Before push of table elimination, the test case crashes the server, so the table elimination push fixes the crash, but produces wrong/strange output. I will push the test case into lp:maria with wrong/strange result file (to not block the merge of MySQL 5.1.38). This needs to be updated after fixing the bug: === modified file 'mysql-test/r/subselect3.result' --- mysql-test/r/subselect3.result 2009-08-13 20:33:00 +0000 +++ mysql-test/r/subselect3.result 2009-09-16 11:27:55 +0000 @@ -864,7 +864,7 @@ Level Code Message Note 1276 Field or reference 'test.t1.a' of SELECT #3 was resolved in SELECT #2 Note 1276 Field or reference 'test.t1.c' of SELECT #3 was resolved in SELECT #2 Error 1054 Unknown column 'c' in 'field list' +Note 1003 select `c` AS `c` from (select (select count(`test`.`t1`.`a`) AS `COUNT(a)` from (select count(`test`.`t1`.`b`) AS `COUNT(b)` from `test`.`t1`) `x` group by `t1`.`c`) AS `(SELECT COUNT(a) FROM -Note 1003 select `c` AS `c` from (select (select count(`test`.`t1`.`a`) AS `COUNT(a)` from (select count(`test`.`t1`.`b`) AS `COUNT(b)` from `test`.`t1`) `x` group by `c`) AS `(SELECT COUNT(a) FROM (SELECT COUNT(b) FROM t1) AS x GROUP BY c )` from `test`.`t1` group by `test`.`t1`.`b`) `y` DROP TABLE t1;]]> bug Kristian Nielsen added bug maria: status Kristian Nielsen maria: assignee Kristian Nielsen maria: importance Hakan Küçükyılmaz bug watch added Hakan Küçükyılmaz maria: milestone Sergei maria: importance Sergey Petrunia maria: status Sergey Petrunia Kristian Nielsen Hakan Küçükyılmaz Kristian Nielsen Sergey Petrunia Sergey Petrunia The problem here is this output "group by `t1`.`c`". The column `c` is unknown at that place in the query, so it makes no sense to qualify it with the table name t1. I don't think this is the case. Let's look at the query again: 01 EXPLAIN EXTENDED SELECT c 02 FROM 03 ( 04 SELECT 05 (SELECT COUNT(a) 06 FROM 07 (SELECT COUNT(b) FROM t1) AS x 08 GROUP BY c) 09 FROM 10 t1 11 GROUP BY b 12 ) AS y; The "GROUP BY c" clause we're talking about is on line 8. it belongs to the subquery that is located on lines 5-8 that subquery is a scalar-context subquery that is located in the select list of the subquery that is located on lines 4-11. The subquery on lines 4-11 has a table named "t1", with column t1.c. So, the "GROUP BY c" on line 8 refers to the t1.c of table t1 mentioned on line 10. The "unknown column c" error is produced for the reference to column "c" made from line 1. ]]> Sergey Petrunia Kristian Nielsen