set global innodb_table_locks=1; select @@innodb_table_locks; @@innodb_table_locks 1 drop table if exists t1; set @@innodb_table_locks=1; create table t1 (id integer, x integer) engine=INNODB; insert into t1 values(0, 0); set autocommit=0; SELECT * from t1 where id = 0 FOR UPDATE; id x 0 0 set autocommit=0; lock table t1 write; update t1 set x=1 where id = 0; select * from t1; id x 0 1 commit; update t1 set x=2 where id = 0; commit; unlock tables; select * from t1; id x 0 2 commit; drop table t1; # # Old lock method (where LOCK TABLE was ignored by InnoDB) no longer # works when LOCK TABLE ... WRITE is used due to fix for bugs #46272 # "MySQL 5.4.4, new MDL: unnecessary and bug #37346 "innodb does not # detect deadlock between update and alter table". But it still works # for LOCK TABLE ... READ. # set @@innodb_table_locks=0; create table t1 (id integer primary key, x integer) engine=INNODB; insert into t1 values(0, 0),(1,1),(2,2); commit; SELECT * from t1 where id = 0 FOR UPDATE; id x 0 0 # Connection 'con2'. set autocommit=0; set @@innodb_table_locks=0; # The following statement should block because SQL-level lock # is taken on t1 which will wait until concurrent transaction # is commited. # Sending: lock table t1 write;; # Connection 'con1'. # Wait until LOCK TABLE is blocked on SQL-level lock. # We should be able to do UPDATEs and SELECTs within transaction. update t1 set x=1 where id = 0; select * from t1; id x 0 1 1 1 2 2 # Unblock LOCK TABLE. commit; # Connection 'con2'. # Reap LOCK TABLE. unlock tables; # Connection 'con1'. select * from t1 where id = 0 for update; id x 0 1 # Connection 'con2'. # The below statement should not be blocked as LOCK TABLES ... READ # does not take strong SQL-level lock on t1. SELECTs which do not # conflict with transaction in the first connections should not be # blocked. lock table t1 read; select * from t1; id x 0 1 1 1 2 2 select * from t1 where id = 1 lock in share mode; id x 1 1 unlock tables; select * from t1; id x 0 1 1 1 2 2 commit; # Connection 'con1'. commit; drop table t1; # #Bug#12842206 INNODB LOCKING REGRESSION FOR INSERT IGNORE #fixed by re-fixing Bug#7975 #aka Bug#11759688 52020: InnoDB can still deadlock on just INSERT... # CREATE TABLE t1 (a INT PRIMARY KEY, b INT NOT NULL) ENGINE=InnoDB; INSERT INTO t1 VALUES(3,1); BEGIN; INSERT IGNORE INTO t1 VALUES(3,14); BEGIN; INSERT IGNORE INTO t1 VALUES(3,23); SELECT * FROM t1 FOR UPDATE; COMMIT; a b 3 1 COMMIT; DROP TABLE t1; Bug#19803418 ASSERTION: TABLE->QUIESCE == QUIESCE_NONE IN ROW0QUIESCE.CC LINE 683 CREATE TABLE t1(C TEXT CHARACTER SET UJIS) ENGINE=INNODB; LOCK TABLES t1 WRITE,t1 AS t0 READ,t1 AS t2 READ; FLUSH TABLE t1; LOCK TABLES t1 READ,t1 AS t0 WRITE,t1 AS t2 READ; FLUSH TABLE t1; LOCK TABLES t1 READ,t1 AS t0 READ,t1 AS t2 READ; FLUSH TABLE t1; ERROR HY000: Table 't1' was locked with a READ lock and can't be updated UNLOCK TABLES; FLUSH TABLE t1; DROP TABLE t1;