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Fix Bug #18559 "log tables cannot change engine, and
gets deadlocked when dropping w/ log on"
Log tables rely on concurrent insert machinery to add data.
This means that log tables are always opened and locked by
special (artificial) logger threads. Because of this, the thread
which tries to drop a log table starts to wait for the table
to be unlocked. Which will happen only if the log table is disabled.
Alike situation happens if one tries to alter a log table.
However in addition to the problem above, alter table calls
check_if_locking_is_allowed() routine for the engine. The
routine does not allow alter for the log tables. So, alter
doesn't start waiting forever for logs to be disabled, but
returns with an error.
Another problem is that not all engines could be used for
the log tables. That's because they need concurrent insert.
In this patch we:
(1) Explicitly disallow to drop/alter a log table if it
is currently used by the logger.
(2) Update MyISAM to support log tables
(3) Allow to drop log tables/alter log tables if log is
disabled
At the same time we (4) Disallow to alter log tables to
unsupported engine (after this patch CSV and MyISAM are
alowed)
Recommit with review fixes.
This commit is contained in:
@@ -72,3 +72,144 @@ sleep(2)
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select * from mysql.slow_log;
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start_time user_host query_time lock_time rows_sent rows_examined db last_insert_id insert_id server_id sql_text
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TIMESTAMP USER_HOST QUERY_TIME 00:00:00 1 0 test 0 0 1 select sleep(2)
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alter table mysql.general_log engine=myisam;
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ERROR HY000: You can't alter a log table if logging is enabled
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alter table mysql.slow_log engine=myisam;
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ERROR HY000: You can't alter a log table if logging is enabled
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drop table mysql.general_log;
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ERROR HY000: Cannot drop log table if log is enabled
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drop table mysql.slow_log;
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ERROR HY000: Cannot drop log table if log is enabled
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set global general_log='OFF';
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alter table mysql.slow_log engine=myisam;
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ERROR HY000: You can't alter a log table if logging is enabled
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set global slow_query_log='OFF';
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show create table mysql.general_log;
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Table Create Table
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general_log CREATE TABLE `general_log` (
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`event_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
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`user_host` mediumtext,
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`thread_id` int(11) DEFAULT NULL,
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`server_id` int(11) DEFAULT NULL,
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`command_type` varchar(64) DEFAULT NULL,
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`argument` mediumtext
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) ENGINE=CSV DEFAULT CHARSET=utf8 COMMENT='General log'
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show create table mysql.slow_log;
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Table Create Table
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slow_log CREATE TABLE `slow_log` (
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`start_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
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`user_host` mediumtext NOT NULL,
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`query_time` time NOT NULL,
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`lock_time` time NOT NULL,
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`rows_sent` int(11) NOT NULL,
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`rows_examined` int(11) NOT NULL,
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`db` varchar(512) DEFAULT NULL,
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`last_insert_id` int(11) DEFAULT NULL,
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`insert_id` int(11) DEFAULT NULL,
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`server_id` int(11) DEFAULT NULL,
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`sql_text` mediumtext NOT NULL
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) ENGINE=CSV DEFAULT CHARSET=utf8 COMMENT='Slow log'
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alter table mysql.general_log engine=myisam;
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alter table mysql.slow_log engine=myisam;
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Warnings:
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Warning 1264 Out of range value for column 'last_insert_id' at row 0
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Warning 1264 Out of range value for column 'insert_id' at row 0
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show create table mysql.general_log;
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Table Create Table
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general_log CREATE TABLE `general_log` (
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`event_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
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`user_host` mediumtext,
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`thread_id` int(11) DEFAULT NULL,
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`server_id` int(11) DEFAULT NULL,
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`command_type` varchar(64) DEFAULT NULL,
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`argument` mediumtext
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) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT='General log'
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show create table mysql.slow_log;
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Table Create Table
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slow_log CREATE TABLE `slow_log` (
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`start_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
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`user_host` mediumtext NOT NULL,
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`query_time` time NOT NULL,
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`lock_time` time NOT NULL,
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`rows_sent` int(11) NOT NULL,
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`rows_examined` int(11) NOT NULL,
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`db` varchar(512) DEFAULT NULL,
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`last_insert_id` int(11) DEFAULT NULL,
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`insert_id` int(11) DEFAULT NULL,
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`server_id` int(11) DEFAULT NULL,
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`sql_text` mediumtext NOT NULL
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) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT='Slow log'
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set global general_log='ON';
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set global slow_query_log='ON';
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select * from mysql.general_log;
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event_time user_host thread_id server_id command_type argument
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TIMESTAMP USER_HOST THREAD_ID 1 Query set names utf8
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TIMESTAMP USER_HOST THREAD_ID 1 Query create table bug16905 (s char(15) character set utf8 default 'пусто')
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TIMESTAMP USER_HOST THREAD_ID 1 Query insert into bug16905 values ('новое')
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TIMESTAMP USER_HOST THREAD_ID 1 Query select * from mysql.general_log
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TIMESTAMP USER_HOST THREAD_ID 1 Query drop table bug16905
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TIMESTAMP USER_HOST THREAD_ID 1 Query truncate table mysql.slow_log
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TIMESTAMP USER_HOST THREAD_ID 1 Query set session long_query_time=1
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TIMESTAMP USER_HOST THREAD_ID 1 Query select sleep(2)
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TIMESTAMP USER_HOST THREAD_ID 1 Query select * from mysql.slow_log
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TIMESTAMP USER_HOST THREAD_ID 1 Query alter table mysql.general_log engine=myisam
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TIMESTAMP USER_HOST THREAD_ID 1 Query alter table mysql.slow_log engine=myisam
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TIMESTAMP USER_HOST THREAD_ID 1 Query drop table mysql.general_log
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TIMESTAMP USER_HOST THREAD_ID 1 Query drop table mysql.slow_log
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TIMESTAMP USER_HOST THREAD_ID 1 Query set global general_log='OFF'
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TIMESTAMP USER_HOST THREAD_ID 1 Query set global slow_query_log='ON'
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TIMESTAMP USER_HOST THREAD_ID 1 Query select * from mysql.general_log
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flush logs;
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lock tables mysql.general_log WRITE;
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ERROR HY000: You can't write-lock a log table. Only read access is possible.
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lock tables mysql.slow_log WRITE;
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ERROR HY000: You can't write-lock a log table. Only read access is possible.
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lock tables mysql.general_log READ;
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ERROR HY000: You can't use usual read lock with log tables. Try READ LOCAL instead.
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lock tables mysql.slow_log READ;
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ERROR HY000: You can't use usual read lock with log tables. Try READ LOCAL instead.
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lock tables mysql.slow_log READ LOCAL, mysql.general_log READ LOCAL;
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unlock tables;
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set global general_log='OFF';
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set global slow_query_log='OFF';
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alter table mysql.slow_log engine=ndb;
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ERROR HY000: One can use only CSV and MyISAM engines for the log tables
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alter table mysql.slow_log engine=innodb;
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ERROR HY000: One can use only CSV and MyISAM engines for the log tables
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alter table mysql.slow_log engine=archive;
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ERROR HY000: One can use only CSV and MyISAM engines for the log tables
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alter table mysql.slow_log engine=blackhole;
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ERROR HY000: One can use only CSV and MyISAM engines for the log tables
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drop table mysql.slow_log;
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drop table mysql.general_log;
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drop table mysql.general_log;
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ERROR 42S02: Unknown table 'general_log'
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drop table mysql.slow_log;
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ERROR 42S02: Unknown table 'slow_log'
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use mysql;
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CREATE TABLE `general_log` (
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`event_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
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ON UPDATE CURRENT_TIMESTAMP,
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`user_host` mediumtext,
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`thread_id` int(11) DEFAULT NULL,
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`server_id` int(11) DEFAULT NULL,
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`command_type` varchar(64) DEFAULT NULL,
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`argument` mediumtext
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) ENGINE=CSV DEFAULT CHARSET=utf8 COMMENT='General log';
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CREATE TABLE `slow_log` (
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`start_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
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ON UPDATE CURRENT_TIMESTAMP,
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`user_host` mediumtext NOT NULL,
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`query_time` time NOT NULL,
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`lock_time` time NOT NULL,
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`rows_sent` int(11) NOT NULL,
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`rows_examined` int(11) NOT NULL,
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`db` varchar(512) DEFAULT NULL,
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`last_insert_id` int(11) DEFAULT NULL,
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`insert_id` int(11) DEFAULT NULL,
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`server_id` int(11) DEFAULT NULL,
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`sql_text` mediumtext NOT NULL
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) ENGINE=CSV DEFAULT CHARSET=utf8 COMMENT='Slow log';
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set global general_log='ON';
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set global slow_query_log='ON';
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use test;
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