mariadb/mysql-test/r/flush.result

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drop table if exists t1,t2;
drop database if exists mysqltest;
create temporary table t1(n int not null primary key);
create table t2(n int);
insert into t2 values(3);
select * from t1;
n
3
flush tables with read lock;
drop table t2;
ERROR HY000: Can't execute the query because you have a conflicting read lock
drop table t2;
unlock tables;
create database mysqltest;
create table mysqltest.t1(n int);
insert into mysqltest.t1 values (23);
flush tables with read lock;
drop database mysqltest;
select * from mysqltest.t1;
n
23
unlock tables;
create table t1 (n int);
flush tables with read lock;
insert into t1 values (345);
select * from t1;
n
345
drop table t1;
create table t1 (c1 int);
lock table t1 write;
flush tables with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
lock table t1 read;
flush tables with read lock;
Initial import of WL#3726 "DDL locking for all metadata objects". Backport of: ------------------------------------------------------------ revno: 2630.4.1 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Fri 2008-05-23 17:54:03 +0400 message: WL#3726 "DDL locking for all metadata objects". After review fixes in progress. ------------------------------------------------------------ This is the first patch in series. It transforms the metadata locking subsystem to use a dedicated module (mdl.h,cc). No significant changes in the locking protocol. The import passes the test suite with the exception of deprecated/removed 6.0 features, and MERGE tables. The latter are subject to a fix by WL#4144. Unfortunately, the original changeset comments got lost in a merge, thus this import has its own (largely insufficient) comments. This patch fixes Bug#25144 "replication / binlog with view breaks". Warning: this patch introduces an incompatible change: Under LOCK TABLES, it's no longer possible to FLUSH a table that was not locked for WRITE. Under LOCK TABLES, it's no longer possible to DROP a table or VIEW that was not locked for WRITE. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.2 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 14:03:45 +0400 message: WL#3726 "DDL locking for all metadata objects". After review fixes in progress. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.3 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 14:08:51 +0400 message: WL#3726 "DDL locking for all metadata objects" Fixed failing Windows builds by adding mdl.cc to the lists of files needed to build server/libmysqld on Windows. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.4 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 21:57:58 +0400 message: WL#3726 "DDL locking for all metadata objects". Fix for assert failures in kill.test which occured when one tried to kill ALTER TABLE statement on merge table while it was waiting in wait_while_table_is_used() for other connections to close this table. These assert failures stemmed from the fact that cleanup code in this case assumed that temporary table representing new version of table was open with adding to THD::temporary_tables list while code which were opening this temporary table wasn't always fulfilling this. This patch changes code that opens new version of table to always do this linking in. It also streamlines cleanup process for cases when error occurs while we have new version of table open. ****** WL#3726 "DDL locking for all metadata objects" Add libmysqld/mdl.cc to .bzrignore. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.6 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sun 2008-05-25 00:33:22 +0400 message: WL#3726 "DDL locking for all metadata objects". Addition to the fix of assert failures in kill.test caused by changes for this worklog. Make sure we close the new table only once.
2009-11-30 16:55:03 +01:00
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
flush tables with read lock;
lock table t1 write;
ERROR HY000: Can't execute the query because you have a conflicting read lock
lock table t1 read;
lock table t1 write;
ERROR HY000: Can't execute the query because you have a conflicting read lock
unlock tables;
create table t2 (c1 int);
create table t3 (c1 int);
lock table t1 read, t2 read, t3 write;
flush tables with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
lock table t1 read, t2 read, t3 read;
flush tables with read lock;
Initial import of WL#3726 "DDL locking for all metadata objects". Backport of: ------------------------------------------------------------ revno: 2630.4.1 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Fri 2008-05-23 17:54:03 +0400 message: WL#3726 "DDL locking for all metadata objects". After review fixes in progress. ------------------------------------------------------------ This is the first patch in series. It transforms the metadata locking subsystem to use a dedicated module (mdl.h,cc). No significant changes in the locking protocol. The import passes the test suite with the exception of deprecated/removed 6.0 features, and MERGE tables. The latter are subject to a fix by WL#4144. Unfortunately, the original changeset comments got lost in a merge, thus this import has its own (largely insufficient) comments. This patch fixes Bug#25144 "replication / binlog with view breaks". Warning: this patch introduces an incompatible change: Under LOCK TABLES, it's no longer possible to FLUSH a table that was not locked for WRITE. Under LOCK TABLES, it's no longer possible to DROP a table or VIEW that was not locked for WRITE. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.2 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 14:03:45 +0400 message: WL#3726 "DDL locking for all metadata objects". After review fixes in progress. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.3 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 14:08:51 +0400 message: WL#3726 "DDL locking for all metadata objects" Fixed failing Windows builds by adding mdl.cc to the lists of files needed to build server/libmysqld on Windows. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.4 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 21:57:58 +0400 message: WL#3726 "DDL locking for all metadata objects". Fix for assert failures in kill.test which occured when one tried to kill ALTER TABLE statement on merge table while it was waiting in wait_while_table_is_used() for other connections to close this table. These assert failures stemmed from the fact that cleanup code in this case assumed that temporary table representing new version of table was open with adding to THD::temporary_tables list while code which were opening this temporary table wasn't always fulfilling this. This patch changes code that opens new version of table to always do this linking in. It also streamlines cleanup process for cases when error occurs while we have new version of table open. ****** WL#3726 "DDL locking for all metadata objects" Add libmysqld/mdl.cc to .bzrignore. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.6 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sun 2008-05-25 00:33:22 +0400 message: WL#3726 "DDL locking for all metadata objects". Addition to the fix of assert failures in kill.test caused by changes for this worklog. Make sure we close the new table only once.
2009-11-30 16:55:03 +01:00
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
drop table t1, t2, t3;
create table t1 (c1 int);
create table t2 (c1 int);
lock table t1 write;
flush tables with read lock;
insert into t2 values(1);
unlock tables;
drop table t1, t2;
drop table if exists t1, t2;
set session low_priority_updates=1;
create table t1 (a int);
create table t2 (b int);
lock tables t1 write;
flush tables with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
lock tables t1 read, t2 write;
flush tables with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
lock tables t1 read;
flush tables with read lock;
Initial import of WL#3726 "DDL locking for all metadata objects". Backport of: ------------------------------------------------------------ revno: 2630.4.1 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Fri 2008-05-23 17:54:03 +0400 message: WL#3726 "DDL locking for all metadata objects". After review fixes in progress. ------------------------------------------------------------ This is the first patch in series. It transforms the metadata locking subsystem to use a dedicated module (mdl.h,cc). No significant changes in the locking protocol. The import passes the test suite with the exception of deprecated/removed 6.0 features, and MERGE tables. The latter are subject to a fix by WL#4144. Unfortunately, the original changeset comments got lost in a merge, thus this import has its own (largely insufficient) comments. This patch fixes Bug#25144 "replication / binlog with view breaks". Warning: this patch introduces an incompatible change: Under LOCK TABLES, it's no longer possible to FLUSH a table that was not locked for WRITE. Under LOCK TABLES, it's no longer possible to DROP a table or VIEW that was not locked for WRITE. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.2 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 14:03:45 +0400 message: WL#3726 "DDL locking for all metadata objects". After review fixes in progress. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.3 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 14:08:51 +0400 message: WL#3726 "DDL locking for all metadata objects" Fixed failing Windows builds by adding mdl.cc to the lists of files needed to build server/libmysqld on Windows. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.4 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sat 2008-05-24 21:57:58 +0400 message: WL#3726 "DDL locking for all metadata objects". Fix for assert failures in kill.test which occured when one tried to kill ALTER TABLE statement on merge table while it was waiting in wait_while_table_is_used() for other connections to close this table. These assert failures stemmed from the fact that cleanup code in this case assumed that temporary table representing new version of table was open with adding to THD::temporary_tables list while code which were opening this temporary table wasn't always fulfilling this. This patch changes code that opens new version of table to always do this linking in. It also streamlines cleanup process for cases when error occurs while we have new version of table open. ****** WL#3726 "DDL locking for all metadata objects" Add libmysqld/mdl.cc to .bzrignore. ****** Backport of: ------------------------------------------------------------ revno: 2630.4.6 committer: Dmitry Lenev <dlenev@mysql.com> branch nick: mysql-6.0-3726-w timestamp: Sun 2008-05-25 00:33:22 +0400 message: WL#3726 "DDL locking for all metadata objects". Addition to the fix of assert failures in kill.test caused by changes for this worklog. Make sure we close the new table only once.
2009-11-30 16:55:03 +01:00
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
drop table t1, t2;
set session low_priority_updates=default;
select benchmark(200, (select sin(1))) > 1000;
End of 5.0 tests
set @old_general_log= @@general_log;
set @old_read_only= @@read_only;
set global general_log= on;
flush tables with read lock;
flush logs;
unlock tables;
set global read_only=1;
flush logs;
unlock tables;
flush tables with read lock;
flush logs;
unlock tables;
set global general_log= @old_general_log;
set global read_only= @old_read_only;
End of 5.1 tests
#
# Additional test for bug #51136 "Crash in pthread_rwlock_rdlock
# on TEMPORARY + HANDLER + LOCK + SP".
# Also see the main test for this bug in include/handler.inc.
#
drop tables if exists t1, t2;
create table t1 (i int);
create temporary table t2 (j int);
flush tables with read lock;
lock table t2 read;
# This commit should not release any MDL locks.
commit;
# The below statement crashed before the bug fix as it
# has attempted to release global shared metadata lock
# which was already released by commit.
unlock tables;
drop tables t1, t2;
#
# Tests for WL#5000 FLUSH TABLES|TABLE table_list WITH READ LOCK
#
# I. Check the incompatible changes in the grammar.
#
flush tables with read lock, hosts;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ' hosts' at line 1
flush privileges, tables;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tables' at line 1
flush privileges, tables with read lock;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tables with read lock' at line 1
flush privileges, tables;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tables' at line 1
flush tables with read lock, tables;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ' tables' at line 1
show tables;
Tables_in_test
#
# II. Check the allowed syntax.
#
drop table if exists t1, t2, t3;
create table t1 (a int);
create table t2 (a int);
create table t3 (a int);
lock table t1 read, t2 read;
flush tables with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
flush tables with read lock;
flush tables t1, t2 with read lock;
flush tables t1, t2 with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
flush tables with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
select * from t1;
a
select * from t2;
a
select * from t3;
ERROR HY000: Table 't3' was not locked with LOCK TABLES
insert into t1 (a) values (1);
ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
insert into t2 (a) values (1);
ERROR HY000: Table 't2' was locked with a READ lock and can't be updated
insert into t3 (a) values (1);
ERROR HY000: Table 't3' was not locked with LOCK TABLES
lock table no_such_table read;
ERROR 42S02: Table 'test.no_such_table' doesn't exist
#
# We implicitly left the locked tables
# mode but still have the read lock.
#
insert into t2 (a) values (1);
ERROR HY000: Can't execute the query because you have a conflicting read lock
unlock tables;
insert into t1 (a) values (1);
insert into t2 (a) values (1);
flush table t1, t2 with read lock;
select * from t1;
a
1
select * from t2;
a
1
select * from t3;
ERROR HY000: Table 't3' was not locked with LOCK TABLES
insert into t1 (a) values (2);
ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
insert into t2 (a) values (2);
ERROR HY000: Table 't2' was locked with a READ lock and can't be updated
insert into t3 (a) values (2);
ERROR HY000: Table 't3' was not locked with LOCK TABLES
lock table no_such_table read;
ERROR 42S02: Table 'test.no_such_table' doesn't exist
insert into t3 (a) values (2);
#
# III. Concurrent tests.
#
# --> connection default
#
# Check that flush tables <list> with read lock
# does not affect non-locked tables.
#
flush tables t1 with read lock;
# --> connection con1;
select * from t1;
a
1
select * from t2;
a
1
insert into t2 (a) values (3);
# --> connection default;
unlock tables;
Fix for bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". The problem was that FLUSH TABLES <list> WITH READ LOCK which was issued when other connection has acquired global read lock using FLUSH TABLES WITH READ LOCK was blocked and has to wait until global read lock is released. This issue stemmed from the fact that FLUSH TABLES <list> WITH READ LOCK implementation has acquired X metadata locks on tables to be flushed. Since these locks required acquiring of global IX lock this statement was incompatible with global read lock. This patch addresses problem by using SNW metadata type of lock for tables to be flushed by FLUSH TABLES <list> WITH READ LOCK. It is OK to acquire them without global IX lock as long as we won't try to upgrade those locks. Since SNW locks allow concurrent statements using same table FLUSH TABLE <list> WITH READ LOCK now has to wait until old versions of tables to be flushed go away after acquiring metadata locks. Since such waiting can lead to deadlock MDL deadlock detector was extended to take into account waits for flush and resolve such deadlocks. As a bonus code in open_tables() which was responsible for waiting old versions of tables to go away was refactored. Now when we encounter old version of table in open_table() we don't back-off and wait for all old version to go away, but instead wait for this particular table to be flushed. Such approach supported by deadlock detection should reduce number of scenarios in which FLUSH TABLES aborts concurrent multi-statement transactions. Note that active FLUSH TABLES <list> WITH READ LOCK still blocks concurrent FLUSH TABLES WITH READ LOCK statement as the former keeps tables open and thus prevents the latter statement from doing flush.
2010-07-27 15:34:58 +02:00
#
# Check that "FLUSH TABLES <list> WITH READ LOCK" is
# compatible with active "FLUSH TABLES WITH READ LOCK".
# Vice versa it is not true, since tables read-locked by
# "FLUSH TABLES <list> WITH READ LOCK" can't be flushed.
Fix for bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES <list> WITH READ LOCK are incompatible". The problem was that FLUSH TABLES <list> WITH READ LOCK which was issued when other connection has acquired global read lock using FLUSH TABLES WITH READ LOCK was blocked and has to wait until global read lock is released. This issue stemmed from the fact that FLUSH TABLES <list> WITH READ LOCK implementation has acquired X metadata locks on tables to be flushed. Since these locks required acquiring of global IX lock this statement was incompatible with global read lock. This patch addresses problem by using SNW metadata type of lock for tables to be flushed by FLUSH TABLES <list> WITH READ LOCK. It is OK to acquire them without global IX lock as long as we won't try to upgrade those locks. Since SNW locks allow concurrent statements using same table FLUSH TABLE <list> WITH READ LOCK now has to wait until old versions of tables to be flushed go away after acquiring metadata locks. Since such waiting can lead to deadlock MDL deadlock detector was extended to take into account waits for flush and resolve such deadlocks. As a bonus code in open_tables() which was responsible for waiting old versions of tables to go away was refactored. Now when we encounter old version of table in open_table() we don't back-off and wait for all old version to go away, but instead wait for this particular table to be flushed. Such approach supported by deadlock detection should reduce number of scenarios in which FLUSH TABLES aborts concurrent multi-statement transactions. Note that active FLUSH TABLES <list> WITH READ LOCK still blocks concurrent FLUSH TABLES WITH READ LOCK statement as the former keeps tables open and thus prevents the latter statement from doing flush.
2010-07-27 15:34:58 +02:00
flush tables with read lock;
# --> connection con1;
flush table t1 with read lock;
select * from t1;
a
1
unlock tables;
# --> connection default;
unlock tables;
#
# Check that FLUSH TABLES t1 WITH READ LOCK
# does not conflict with an existing FLUSH TABLES t2
# WITH READ LOCK.
#
flush table t1 with read lock;
# --> connection con1
flush table t2 with read lock;
unlock tables;
# --> connection default
unlock tables;
#
# Check that FLUSH TABLES t1 WITH READ LOCK
# does not conflict with SET GLOBAL read_only=1.
#
set global read_only=1;
# connection con1
flush table t1 with read lock;
unlock tables;
# connection default
set global read_only=0;
#
# Check that it's possible to read-lock
# tables locked with FLUSH TABLE <list> WITH READ LOCK.
#
flush tables t1, t2 with read lock;
# connection con1
lock table t1 read, t2 read;
unlock tables;
# connection default
unlock tables;
# --> connection con1
drop table t1, t2, t3;
#
# Bug#51710 FLUSH TABLES <view> WITH READ LOCK kills the server
#
drop view if exists v1, v2, v3;
drop table if exists t1, v1;
create table t1 (a int);
create view v1 as select 1;
create view v2 as select * from t1;
create view v3 as select * from v2;
flush table v1, v2, v3 with read lock;
ERROR HY000: 'test.v1' is not BASE TABLE
flush table v1 with read lock;
ERROR HY000: 'test.v1' is not BASE TABLE
flush table v2 with read lock;
ERROR HY000: 'test.v2' is not BASE TABLE
flush table v3 with read lock;
ERROR HY000: 'test.v3' is not BASE TABLE
create temporary table v1 (a int);
flush table v1 with read lock;
ERROR HY000: 'test.v1' is not BASE TABLE
drop view v1;
create table v1 (a int);
flush table v1 with read lock;
drop temporary table v1;
unlock tables;
drop view v2, v3;
drop table t1, v1;
#
# FLUSH TABLES <list> WITH READ LOCK and HANDLER
#
drop table if exists t1;
create table t1 (a int, key a (a));
insert into t1 (a) values (1), (2), (3);
handler t1 open;
handler t1 read a next;
a
1
handler t1 read a next;
a
2
flush tables t1 with read lock;
handler t1 read a next;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
#
# Sic: lost handler position.
#
handler t1 read a next;
a
1
handler t1 close;
drop table t1;
#
# Bug#52117 Pending FLUSH TALBES <list> aborts
# transactions unnecessarily.
#
drop table if exists t1;
# --> conection default
create table t1 (a int);
begin;
select * from t1;
a
# --> connection con1
#
# Issue a LOCK TABLE t1 READ. We could use HANDLER t1 OPEN
# or a long-running select -- anything that
# prevents FLUSH TABLE t1 from immediate completion would do.
#
lock table t1 read;
# --> connection con2
#
# FLUSH TABLE expels the table definition from the cache.
# Sending 'flush table t1'...
flush table t1;
# --> connection default
# Let flush table sync in.
select * from t1;
# --> connection con1
select * from t1;
a
unlock tables;
# --> connection con2
# Reaping 'flush table t1'...
# --> connection default
# Reaping 'select * from t1'...
a
commit;
#
# Repeat the same test but with FLUSH TABLES
#
begin;
select * from t1;
a
# --> connection con1
#
# Issue a LOCK TABLE t1 READ.
#
lock table t1 read;
# --> connection con2
#
# FLUSH TABLES expels the table definition from the cache.
# Sending 'flush tables'...
flush tables;
# --> connection default
# Let flush table sync in.
select * from t1;
# --> connection con1
select * from t1;
a
unlock tables;
# --> connection con2
# Reaping 'flush tables'...
# --> connection default
# Reaping 'select * from t1'...
a
commit;
# Cleanup
# --> connection con1
# --> connection con2
# --> connection default
drop table t1;
#
# Test for bug #55273 "FLUSH TABLE tm WITH READ LOCK for Merge table
# causes assert failure".
#
drop table if exists t1, t2, tm;
create table t1 (i int);
create table t2 (i int);
create table tm (i int) engine=merge union=(t1, t2);
insert into t1 values (1), (2);
insert into t2 values (3), (4);
# The below statement should succeed and lock merge
# table for read. Only merge table gets flushed and
# not underlying tables.
flush tables tm with read lock;
select * from tm;
i
1
2
3
4
# Check that underlying tables are locked.
select * from t1;
i
1
2
select * from t2;
i
3
4
unlock tables;
# This statement should succeed as well and flush
# all tables in the list.
flush tables tm, t1, t2 with read lock;
select * from tm;
i
1
2
3
4
# Naturally, underlying tables should be locked in this case too.
select * from t1;
i
1
2
select * from t2;
i
3
4
unlock tables;
drop tables tm, t1, t2;
Patch that refactors global read lock implementation and fixes bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ LOCK" and bug #54673 "It takes too long to get readlock for 'FLUSH TABLES WITH READ LOCK'". The first bug manifested itself as a deadlock which occurred when a connection, which had some table open through HANDLER statement, tried to update some data through DML statement while another connection tried to execute FLUSH TABLES WITH READ LOCK concurrently. What happened was that FTWRL in the second connection managed to perform first step of GRL acquisition and thus blocked all upcoming DML. After that it started to wait for table open through HANDLER statement to be flushed. When the first connection tried to execute DML it has started to wait for GRL/the second connection creating deadlock. The second bug manifested itself as starvation of FLUSH TABLES WITH READ LOCK statements in cases when there was a constant stream of concurrent DML statements (in two or more connections). This has happened because requests for protection against GRL which were acquired by DML statements were ignoring presence of pending GRL and thus the latter was starved. This patch solves both these problems by re-implementing GRL using metadata locks. Similar to the old implementation acquisition of GRL in new implementation is two-step. During the first step we block all concurrent DML and DDL statements by acquiring global S metadata lock (each DML and DDL statement acquires global IX lock for its duration). During the second step we block commits by acquiring global S lock in COMMIT namespace (commit code acquires global IX lock in this namespace). Note that unlike in old implementation acquisition of protection against GRL in DML and DDL is semi-automatic. We assume that any statement which should be blocked by GRL will either open and acquires write-lock on tables or acquires metadata locks on objects it is going to modify. For any such statement global IX metadata lock is automatically acquired for its duration. The first problem is solved because waits for GRL become visible to deadlock detector in metadata locking subsystem and thus deadlocks like one in the first bug become impossible. The second problem is solved because global S locks which are used for GRL implementation are given preference over IX locks which are acquired by concurrent DML (and we can switch to fair scheduling in future if needed). Important change: FTWRL/GRL no longer blocks DML and DDL on temporary tables. Before this patch behavior was not consistent in this respect: in some cases DML/DDL statements on temporary tables were blocked while in others they were not. Since the main use cases for FTWRL are various forms of backups and temporary tables are not preserved during backups we have opted for consistently allowing DML/DDL on temporary tables during FTWRL/GRL. Important change: This patch changes thread state names which are used when DML/DDL of FTWRL is waiting for global read lock. It is now either "Waiting for global read lock" or "Waiting for commit lock" depending on the stage on which FTWRL is. Incompatible change: To solve deadlock in events code which was exposed by this patch we have to replace LOCK_event_metadata mutex with metadata locks on events. As result we have to prohibit DDL on events under LOCK TABLES. This patch also adds extensive test coverage for interaction of DML/DDL and FTWRL. Performance of new and old global read lock implementations in sysbench tests were compared. There were no significant difference between new and old implementations.
2010-11-11 18:11:05 +01:00
#
# Test for bug #57006 "Deadlock between HANDLER and
# FLUSH TABLES WITH READ LOCK".
#
drop table if exists t1, t2;
create table t1 (i int);
create table t2 (i int);
handler t1 open;
# Switching to connection 'con1'.
# Sending:
flush tables with read lock;
# Switching to connection 'con2'.
# Wait until FTWRL starts waiting for 't1' to be closed.
# Switching to connection 'default'.
# The below statement should not cause deadlock.
# Sending:
insert into t2 values (1);
# Switching to connection 'con2'.
# Wait until INSERT starts to wait for FTWRL to go away.
# Switching to connection 'con1'.
# FTWRL should be able to continue now.
# Reap FTWRL.
unlock tables;
# Switching to connection 'default'.
# Reap INSERT.
handler t1 close;
# Cleanup.
drop tables t1, t2;
#
# Bug#57649 FLUSH TABLES under FLUSH TABLES <list> WITH READ LOCK leads
# to assert failure.
#
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT);
FLUSH TABLES t1 WITH READ LOCK;
FLUSH TABLES;
ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
CREATE TRIGGER t1_bi BEFORE INSERT ON t1 FOR EACH ROW SET @a= 1;
ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
ALTER TABLE t1 COMMENT 'test';
ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
UNLOCK TABLES;
DROP TABLE t1;
Fix for bug #12641342 - "61401: UPDATE PERFORMANCE DEGRADES GRADUALLY IF A TRIGGER EXISTS". This bug manifested itself in two ways: - Firstly execution of any data-changing statement which required prelocking (i.e. involved stored function or trigger) as part of transaction slowed down a bit all subsequent statements in this transaction. So performance in transaction which periodically involved such statements gradually degraded over time. - Secondly execution of any data-changing statement which required prelocking as part of transaction prevented concurrent FLUSH TABLES WITH READ LOCK from proceeding until the end of transaction instead of end of particular statement. The problem was caused by incorrect handling of metadata lock used in FTWRL implementation for statements requiring prelocked mode. Each statement which changes data acquires global IX lock with STATEMENT duration. This lock is supposed to block concurrent FTWRL from proceeding until the statement ends. When entering prelocked mode, durations of all metadata locks acquired so far were changed to EXPLICIT, to prevent substatements from releasing these locks. When prelocked mode was left, durations of metadata locks were changed to TRANSACTIONAL (with a few exceptions) so they can be properly released at the end of transaction. Unfortunately, this meant that the global IX lock blocking FTWRL with STATEMENT duration was moved to TRANSACTIONAL duration after execution of statement requiring prelocking. Since each subsequent statement that required prelocking and tried to acquire global IX lock with STATEMENT duration got a new instance of MDL_ticket, which was later moved to TRANSACTIONAL duration, this led to unwarranted growth of number of tickets with TRANSACITONAL duration in this connection's MDL_context. As result searching for other tickets in it became slow and acquisition of other metadata locks by this transaction started to hog CPU. Moreover, this also meant that after execution of statement requiring prelocking concurrent FTWRL was blocked until the end of transaction instead of end of statement. This patch solves this problem by not moving locks to EXPLICIT duration when thread enters prelocked mode (unless it is a real LOCK TABLES mode). This step turned out to be not really necessary as substatements don't try to release metadata locks. Consequently, the global IX lock blocking FTWRL keeps its STATEMENT duration and is properly released at the end of statement and the above issue goes away.
2011-06-16 17:18:16 +02:00
#
# Test for bug #12641342 - "61401: UPDATE PERFORMANCE DEGRADES
# GRADUALLY IF A TRIGGER EXISTS".
#
# One of side-effects of this bug was that a transaction which
# involved DML statements requiring prelocking blocked concurrent
# FLUSH TABLES WITH READ LOCK for the whole its duration, while
# correct behavior in this case is to block FTWRL only for duration
# of individual DML statements.
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (id INT PRIMARY KEY, value INT);
INSERT INTO t1 VALUES (1, 1);
CREATE TRIGGER t1_au AFTER UPDATE ON t1 FOR EACH ROW SET @var = "a";
BEGIN;
UPDATE t1 SET value= value + 1 WHERE id = 1;
# Switching to connection 'con1'.
# The below FLUSH TABLES WITH READ LOCK should succeed and
# should not be blocked by the transaction in default connection.
FLUSH TABLES WITH READ LOCK;
UNLOCK TABLES;
# Switching to connection 'default'.
COMMIT;
DROP TABLE t1;