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8cf7e3459d
MDEV-17772 - 3 way lock : ALTER, MDL, BACKUP STAGE BLOCK_DDL While waiting for a (potentially long) RO transaction or SELECT, DDL and LOCK TABLES ... WRITE hold protection against FTWRL and BACKUP STAGE. This effectively makes FTWRL/BACKUP STAGE indirectly wait for this RO transaction or SELECT to finish. Which is not great, as otherwise we could do something useful meanwhile. With this patch BACKUP lock is attempted to be acquired after TABLE/SCHEMA locks. If this attempt fails, TABLE/SCHEMA locks gets released and we start waiting for BACKUP lock. When wait finishes, BACKUP lock is released (to avoid deadlocks) and we attempt to acquire all locks once again. Other changes: - Take MDL lock before testing if table exists as part of CREATE TABLE ... IF EXISTS. This change was an effect of changes in lock_table_name and removes an inconsistency where one could get different error messages from CREATE TABLE .. IF EXISTS depending on active mdl locks. One effect of this change is that we don't binary log CREATE TABLE IF EXISTS if the table exists. This was done because old code was sometimes behaving inconsistenly (it was logged some time and not other times) and sending the query to the slave could make the slave even more inconsistent as there is not guarantee that the new table will have the same definition as the old table on the master.
219 lines
6.4 KiB
Text
219 lines
6.4 KiB
Text
#
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# Testing which locks we get from all stages
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#
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BACKUP STAGE START;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_START Backup lock
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BACKUP STAGE FLUSH;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_FLUSH Backup lock
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BACKUP STAGE BLOCK_DDL;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_WAIT_DDL Backup lock
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BACKUP STAGE BLOCK_COMMIT;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_WAIT_COMMIT Backup lock
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BACKUP STAGE END;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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#
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# testing BACKUP STAGE LOCK's
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#
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connect con1,localhost,root,,;
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connect con2,localhost,root,,;
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connection default;
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#
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# testing if BACKUP STAGE FLUSH causes deadlocks with ALTER TABLE
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#
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create table t1 (a int) engine=innodb;
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start transaction;
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insert into t1 values (1);
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connection con1;
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alter table t1 add column (j int), algorithm copy;
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connection con2;
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backup stage start;
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backup stage flush;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_DDL Backup lock
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MDL_BACKUP_FLUSH Backup lock
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MDL_SHARED_WRITE Table metadata lock test t1
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MDL_SHARED_UPGRADABLE Table metadata lock test t1
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MDL_INTENTION_EXCLUSIVE Schema metadata lock test
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SET STATEMENT max_statement_time=1 FOR backup stage block_ddl;
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ERROR 70100: Query execution was interrupted (max_statement_time exceeded)
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backup stage block_ddl;
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connection default;
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commit;
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SELECT * FROM t1;
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a
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1
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SET STATEMENT lock_wait_timeout=0 FOR INSERT INTO t1 values (2);
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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INSERT INTO t1 values (2,0);;
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connection con2;
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backup stage end;
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connection con1;
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connection default;
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select * from t1;
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a j
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1 NULL
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2 0
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drop table t1;
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# Test with inline alter table, which doesn't block block_commit
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create table t1 (a int) engine=innodb;
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start transaction;
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insert into t1 values (1);
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connection con1;
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alter table t1 add column (j int);
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connection con2;
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backup stage start;
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backup stage flush;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_ALTER_COPY Backup lock
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MDL_BACKUP_FLUSH Backup lock
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MDL_SHARED_WRITE Table metadata lock test t1
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MDL_SHARED_UPGRADABLE Table metadata lock test t1
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MDL_INTENTION_EXCLUSIVE Schema metadata lock test
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backup stage block_ddl;
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backup stage block_commit;
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connection default;
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SELECT * FROM t1;
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a
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1
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commit;
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connection con2;
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backup stage end;
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connection con1;
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connection default;
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drop table t1;
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#
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# testing if BACKUP STAGE FLUSH causes deadlocks with DROP TABLE
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#
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create table t1 (a int) engine=innodb;
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start transaction;
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insert into t1 values (1);
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connection con1;
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SET STATEMENT lock_wait_timeout=0 FOR DROP TABLE t1;
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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DROP TABLE t1;
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connection con2;
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backup stage start;
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backup stage flush;
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SET STATEMENT lock_wait_timeout=0 FOR SELECT * FROM t1;
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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backup stage block_ddl;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_WAIT_DDL Backup lock
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MDL_SHARED_WRITE Table metadata lock test t1
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MDL_INTENTION_EXCLUSIVE Schema metadata lock test
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backup stage end;
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connection default;
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commit;
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connection con1;
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connection default;
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#
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# Check if backup stage block_dll + concurrent drop table blocks select
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#
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create table t1 (a int) engine=innodb;
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backup stage start;
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backup stage block_ddl;
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connection con1;
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DROP TABLE t1;
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connection con2;
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connection con2;
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SELECT LOCK_MODE, LOCK_TYPE, TABLE_SCHEMA, TABLE_NAME FROM information_schema.metadata_lock_info;
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LOCK_MODE LOCK_TYPE TABLE_SCHEMA TABLE_NAME
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MDL_BACKUP_WAIT_DDL Backup lock
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SELECT * FROM t1;
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a
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connection default;
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backup stage end;
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connection con1;
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connection default;
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#
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# Check if backup stage block_dll overrides ddl lock for drop table
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#
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create table t1 (a int) engine=innodb;
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start transaction;
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insert into t1 values (1);
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connection con1;
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SET STATEMENT lock_wait_timeout=0 FOR DROP TABLE t1;
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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DROP TABLE t1;
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connection con2;
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backup stage start;
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backup stage flush;
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backup stage block_ddl;
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connection default;
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commit;
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connection con2;
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backup stage end;
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connection con1;
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connection default;
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#
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# Check if BACKUP STAGE BLOCK_COMMIT blocks commit
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#
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create table t1 (a int) engine=innodb;
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start transaction;
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insert into t1 values (1);
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connection con1;
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backup stage start;
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backup stage block_commit;
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connection default;
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commit;
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connection con1;
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backup stage end;
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connection default;
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select * from t1;
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a
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1
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drop table t1;
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disconnect con1;
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disconnect con2;
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#
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# Test backup stage and flush tables
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#
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BACKUP STAGE START ;
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BACKUP STAGE BLOCK_DDL ;
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FLUSH TABLES;
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CREATE TEMPORARY TABLE t12345678_tmp (col1 INT);
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drop table t12345678_tmp;
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BACKUP STAGE END;
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#
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# Test BACKUP STAGES with lock timeouts
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#
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SET GLOBAL lock_wait_timeout=0;
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CREATE TABLE t_permanent_innodb (col1 INT) ENGINE = InnoDB;
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CREATE TABLE t_permanent_myisam (col1 INT) ENGINE = MyISAM;
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INSERT INTO t_permanent_innodb SET col1 = 1;
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INSERT INTO t_permanent_myisam SET col1 = 1;
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CREATE TABLE t_con1_innodb (col1 INT) ENGINE = InnoDB;
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CREATE TABLE t_con1_myisam (col1 INT) ENGINE = MyISAM;
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connect con1,localhost,root,,;
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SET AUTOCOMMIT = 0;
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connection default;
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BACKUP STAGE START;
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BACKUP STAGE FLUSH;
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BACKUP STAGE BLOCK_DDL;
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BACKUP STAGE BLOCK_COMMIT;
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connection con1;
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UPDATE t_permanent_innodb SET col1 = 8;
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UPDATE t_permanent_myisam SET col1 = 8;
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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DROP TABLE t_con1_innodb;
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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DROP TABLE t_con1_myisam;
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ERROR HY000: Lock wait timeout exceeded; try restarting transaction
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connection default;
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BACKUP STAGE END;
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DROP TABLE t_permanent_myisam, t_permanent_innodb;
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DROP TABLE t_con1_innodb, t_con1_myisam;
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disconnect con1;
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set global lock_wait_timeout=default;
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