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https://github.com/MariaDB/server.git
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91 lines
2 KiB
Text
91 lines
2 KiB
Text
set global innodb_table_locks=1;
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select @@innodb_table_locks;
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@@innodb_table_locks
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1
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drop table if exists t1;
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set @@innodb_table_locks=1;
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create table t1 (id integer, x integer) engine=INNODB;
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insert into t1 values(0, 0);
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set autocommit=0;
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SELECT * from t1 where id = 0 FOR UPDATE;
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id x
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0 0
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set autocommit=0;
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lock table t1 write;
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update t1 set x=1 where id = 0;
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select * from t1;
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id x
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0 1
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commit;
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update t1 set x=2 where id = 0;
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commit;
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unlock tables;
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select * from t1;
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id x
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0 2
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commit;
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drop table t1;
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#
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# Old lock method (where LOCK TABLE was ignored by InnoDB) no longer
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# works when LOCK TABLE ... WRITE is used due to fix for bugs #46272
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# "MySQL 5.4.4, new MDL: unnecessary and bug #37346 "innodb does not
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# detect deadlock between update and alter table". But it still works
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# for LOCK TABLE ... READ.
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#
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set @@innodb_table_locks=0;
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create table t1 (id integer primary key, x integer) engine=INNODB;
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insert into t1 values(0, 0),(1,1),(2,2);
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commit;
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SELECT * from t1 where id = 0 FOR UPDATE;
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id x
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0 0
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# Connection 'con2'.
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set autocommit=0;
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set @@innodb_table_locks=0;
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# The following statement should block because SQL-level lock
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# is taken on t1 which will wait until concurrent transaction
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# is commited.
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# Sending:
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lock table t1 write;;
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# Connection 'con1'.
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# Wait until LOCK TABLE is blocked on SQL-level lock.
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# We should be able to do UPDATEs and SELECTs within transaction.
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update t1 set x=1 where id = 0;
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select * from t1;
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id x
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0 1
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1 1
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2 2
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# Unblock LOCK TABLE.
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commit;
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# Connection 'con2'.
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# Reap LOCK TABLE.
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unlock tables;
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# Connection 'con1'.
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select * from t1 where id = 0 for update;
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id x
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0 1
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# Connection 'con2'.
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# The below statement should not be blocked as LOCK TABLES ... READ
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# does not take strong SQL-level lock on t1. SELECTs which do not
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# conflict with transaction in the first connections should not be
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# blocked.
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lock table t1 read;
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select * from t1;
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id x
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0 1
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1 1
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2 2
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select * from t1 where id = 1 lock in share mode;
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id x
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1 1
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unlock tables;
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select * from t1;
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id x
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0 1
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1 1
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2 2
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commit;
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# Connection 'con1'.
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commit;
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drop table t1;
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