Details
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Bug
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Status: Open (View Workflow)
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Major
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Resolution: Unresolved
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10.3(EOL), 10.4(EOL), 10.5, 10.6, 10.8(EOL), 10.9(EOL), 10.10(EOL), 10.11, 11.0(EOL)
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None
Description
Note: If MDEV-31206 is fixed first and the queries become faster, the test case below may no longer do what it is meant to do (the query will end before max_statement_time exceeds); but it's just the matter of the size and the timeout, adjust accordingly if it happens.
SET max_recursive_iterations = 100000; |
drop table if exists t; |
create table t as with recursive cte as (select 1 as a union select a + 1 as a from cte where a < 30000) select * from cte; |
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set max_statement_time= 2; |
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set @start= @@timestamp; |
select max(a) over( ) from t; |
select @@timestamp - @start; |
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drop table t; |
So, without the timeout, currently the query takes ~30 seconds on a release build (and much longer on a debug build).
The test case sets the timeout to 2 seconds, the expected outcome is that the query fails with ER_STATEMENT_TIMEOUT after ~2 seconds.
Instead, it does fail with ER_STATEMENT_TIMEOUT and does not return the result set, but only after the whole execution time, i.e. 30 seconds.
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11.0.1 release |
MariaDB [test]> set max_statement_time= 2; |
Query OK, 0 rows affected (0.000 sec) |
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MariaDB [test]>
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MariaDB [test]> set @start= @@timestamp; |
Query OK, 0 rows affected (0.000 sec) |
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MariaDB [test]> select max(a) over( ) from t; |
ERROR 1969 (70100): Query execution was interrupted (max_statement_time exceeded)
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MariaDB [test]> select @@timestamp - @start; |
+----------------------+ |
| @@timestamp - @start | |
+----------------------+ |
| 31.26440405845642 |
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+----------------------+ |
1 row in set (0.000 sec) |
Same happens with direct KILL [QUERY], whenever it is killed during execution, the query remains in the Killed state approx. its usual execution time, and then fails with ER_QUERY_INTERRUPTED.
MariaDB [test]> show processlist;
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+----+------+-----------------+------+---------+------+--------------+------------------------------+----------+ |
| Id | User | Host | db | Command | Time | State | Info | Progress | |
+----+------+-----------------+------+---------+------+--------------+------------------------------+----------+ |
| 17 | root | localhost:59258 | test | Killed | 22 | Sending data | select max(a) over( ) from t | 0.000 | |
| 18 | root | localhost:40164 | test | Query | 0 | starting | show processlist | 0.000 |
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+----+------+-----------------+------+---------+------+--------------+------------------------------+----------+ |