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MDEV-24452 ALTER TABLE event take infinite time which for example breaks mysql_upgrade

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The problem was that update_timing_fields_for_event() didn't release all
MDL locks it took.
This commit is contained in:
Monty 2021-01-21 16:25:59 +02:00
parent 9930cb22c7
commit 6eb1eed53f
3 changed files with 52 additions and 0 deletions

14
mysql-test/main/alter_events.result Normal file
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@ -0,0 +1,14 @@
SET GLOBAL event_scheduler=1;
CREATE TABLE t1 (a int primary key, b int) engine=innodb;
insert into t1 values (1,1),(2,2),(3,3);
CREATE TABLE t2 (a int primary key) engine=innodb;
CREATE EVENT e_t1 ON SCHEDULE EVERY 1 SECOND DO insert ignore into test.t2 select a from test.t1;
select * from t2;
a
1
2
3
drop event e_t1;
ALTER TABLE mysql.event DROP PRIMARY KEY, ADD PRIMARY KEY(db,name);
drop table t1,t2;
SET GLOBAL event_scheduler=default;

31
mysql-test/main/alter_events.test Normal file
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@ -0,0 +1,31 @@
--source include/not_embedded.inc
--source include/have_innodb.inc
#--source include/have_metadata_lock_info.inc
#
# Testing of problems with ALTER TABLE and events on the same table(s)
#
#
# MDEV-24452 ALTER TABLE event take infinite time which for example breaks
# mysql_upgrade
#
SET GLOBAL event_scheduler=1;
CREATE TABLE t1 (a int primary key, b int) engine=innodb;
insert into t1 values (1,1),(2,2),(3,3);
CREATE TABLE t2 (a int primary key) engine=innodb;
CREATE EVENT e_t1 ON SCHEDULE EVERY 1 SECOND DO insert ignore into test.t2 select a from test.t1;
let $wait_condition=SELECT count(*) > 0 from t2;
--source include/wait_condition.inc
select * from t2;
drop event e_t1;
# select * from information_schema.metadata_lock_info;
ALTER TABLE mysql.event DROP PRIMARY KEY, ADD PRIMARY KEY(db,name);
drop table t1,t2;
SET GLOBAL event_scheduler=default;

7
sql/event_db_repository.cc
View file

@ -1130,6 +1130,12 @@ update_timing_fields_for_event(THD *thd,
DBUG_ASSERT(thd->security_ctx->master_access & PRIV_IGNORE_READ_ONLY);
/*
Take a savepoint to release only the lock on mysql.event
table at the end but keep the global read lock and
possible other locks taken by the caller.
*/
MDL_savepoint mdl_savepoint= thd->mdl_context.mdl_savepoint();
if (open_event_table(thd, TL_WRITE, &table))
DBUG_RETURN(1);
@ -1162,6 +1168,7 @@ update_timing_fields_for_event(THD *thd,
end:
if (thd->commit_whole_transaction_and_close_tables())
ret= 1;
thd->mdl_context.rollback_to_savepoint(mdl_savepoint);
DBUG_RETURN(MY_TEST(ret));
}