mirror of
https://github.com/MariaDB/server.git
synced 2025-02-07 06:12:18 +01:00
4e1e9ea6f3
From the very beginning, the default InnoDB transaction isolation level
REPEATABLE READ does not correspond to any well formed definition.
The main issue is the lack of write/write conflict detection.
To fix that and to make REPEATABLE READ correspond to Snapshot Isolation,
b8a6719889 introduced the Boolean
session variable innodb_snapshot_isolation. It was disabled by default
in order not to break any user applications.
In a new major version of MariaDB Server, we had better enable this
parameter by default.
67 lines
1.7 KiB
Text
67 lines
1.7 KiB
Text
drop table if exists t1,t2;
|
|
connect a,localhost,root,,;
|
|
connect b,localhost,root,,;
|
|
connection a;
|
|
set binlog_format=mixed;
|
|
set session transaction isolation level repeatable read;
|
|
create table t1(a int not null) engine=innodb DEFAULT CHARSET=latin1;
|
|
insert into t1 values (1),(2),(3),(4),(5),(6),(7);
|
|
set autocommit=0;
|
|
select * from t1 where a=3 lock in share mode;
|
|
a
|
|
3
|
|
connection b;
|
|
set binlog_format=mixed;
|
|
set session transaction isolation level repeatable read;
|
|
set autocommit=0;
|
|
update t1 set a=10 where a=5;
|
|
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
|
|
commit;
|
|
connection a;
|
|
commit;
|
|
connection b;
|
|
set innodb_snapshot_isolation=off;
|
|
set session transaction isolation level read committed;
|
|
update t1 set a=10 where a=5;
|
|
connection a;
|
|
select * from t1 where a=2 for update;
|
|
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
|
|
select * from t1 where a=2 limit 1 for update;
|
|
a
|
|
2
|
|
connection b;
|
|
update t1 set a=11 where a=6;
|
|
update t1 set a=12 where a=2;
|
|
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
|
|
update t1 set a=13 where a=1;
|
|
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
|
|
connection a;
|
|
commit;
|
|
connection b;
|
|
update t1 set a=14 where a=1;
|
|
commit;
|
|
connection a;
|
|
select * from t1;
|
|
a
|
|
14
|
|
2
|
|
3
|
|
4
|
|
10
|
|
11
|
|
7
|
|
drop table t1;
|
|
connection default;
|
|
disconnect a;
|
|
disconnect b;
|
|
create table t1 (a int, b int) engine=myisam;
|
|
create table t2 (c int, d int, key (c)) engine=innodb;
|
|
insert into t1 values (1,1);
|
|
insert into t2 values (1,2);
|
|
connect a,localhost,root,,;
|
|
connection a;
|
|
set session transaction isolation level read committed;
|
|
delete from t1 using t1 join t2 on t1.a = t2.c where t2.d in (1);
|
|
connection default;
|
|
disconnect a;
|
|
drop table t1, t2;
|