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1
by brian
clean slate |
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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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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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set autocommit=0;
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set @@innodb_table_locks=0;
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lock table t1 write;
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update t1 set x=10 where id = 2;
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SELECT * from t1 where id = 2;
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id x
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2 2
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UPDATE t1 set x=3 where id = 2;
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commit;
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SELECT * from t1;
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id x
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0 0
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1 1
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2 3
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commit;
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unlock tables;
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commit;
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select * from t1;
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id x
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0 0
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1 1
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2 10
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57 |
drop table t1;
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