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Bug#40536: SELECT is blocked by INSERT DELAYED waiting on

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upgrading lock, even with low_priority_updates

The problem is that there is no mechanism to control whether a
delayed insert takes a high or low priority lock on a table.

The solution is to modify the delayed insert thread ("handler")
to take into account the global value of low_priority_updates
when taking table locks. The value of low_priority_updates is
retrieved when the insert delayed thread is created and will
remain the same for the duration of the thread.
This commit is contained in:
Davi Arnaut
2009-02-03 15:16:24 -02:00
parent 6fb2ba1c3d
commit bc03c9ef19
5 changed files with 81 additions and 5 deletions
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26
mysql-test/r/delayed.result
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@ -284,4 +284,30 @@ ERROR 22007: Incorrect date value: '0000-00-00' for column 'f1' at row 1
INSERT DELAYED INTO t2 VALUES (0,'2007-00-00');
ERROR 22007: Incorrect date value: '2007-00-00' for column 'f1' at row 1
DROP TABLE t1,t2;
set @old_delayed_updates = @@global.low_priority_updates;
set global low_priority_updates = 1;
select @@global.low_priority_updates;
@@global.low_priority_updates
1
drop table if exists t1;
create table t1 (a int, b int);
insert into t1 values (1,1);
lock table t1 read;
connection: update
insert delayed into t1 values (2,2);;
connection: select
select * from t1;
a b
1 1
connection: default
select * from t1;
a b
1 1
unlock tables;
select * from t1;
a b
1 1
2 2
drop table t1;
set global low_priority_updates = @old_delayed_updates;
End of 5.1 tests