database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

MDEV-35124 Set innodb_snapshot_isolation=ON by default

Browse Source 
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.
This commit is contained in:
Marko Mäkelä
2024-10-11 15:02:31 +03:00
parent 26dce1cec3
commit 4e1e9ea6f3
28 changed files with 35 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
mysql-test/suite/innodb/r/deadlock_victim_race.result
View File

@ -10,6 +10,7 @@ SELECT * FROM t WHERE a = 20 FOR UPDATE;
a b
20 20
connect con_2,localhost,root,,;
SET innodb_snapshot_isolation=OFF;
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
BEGIN;
SET DEBUG_SYNC = 'lock_trx_handle_wait_enter SIGNAL upd_locked WAIT_FOR upd_cont EXECUTE 2';

1
mysql-test/suite/innodb/r/deadlock_wait_lock_race.result
View File

@ -8,6 +8,7 @@ SELECT * FROM t WHERE a = 20 FOR UPDATE;
a b
20 20
connect con_2,localhost,root,,;
SET innodb_snapshot_isolation=OFF;
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
BEGIN;
SET DEBUG_SYNC = 'lock_trx_handle_wait_before_unlocked_wait_lock_check SIGNAL upd_locked WAIT_FOR upd_cont';

1
mysql-test/suite/innodb/r/deadlock_wait_thr_race.result
View File

@ -8,6 +8,7 @@ SELECT * FROM t WHERE a = 20 FOR UPDATE;
a b
20 20
connect con_2,localhost,root,,;
SET innodb_snapshot_isolation=OFF;
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
SET DEBUG_SYNC = 'lock_trx_handle_wait_enter SIGNAL upd_locked WAIT_FOR upd_cont';
SET DEBUG_SYNC = 'trx_t_release_locks_enter SIGNAL sel_cont WAIT_FOR upd_cont_2';

2
mysql-test/suite/innodb/r/innodb-isolation.result
View File

@ -80,6 +80,7 @@ COUNT(*)
#
# Do some DML in the default connection and leave the transaction pending.
#
SET innodb_snapshot_isolation=OFF;
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;
BEGIN;
UPDATE t1 SET c2 = c2 * 3 WHERE c1 = 1;
@ -140,6 +141,7 @@ COUNT(*)
# Connection 1 REPEATABLE READ
#
connect con1,localhost,root,,;
SET innodb_snapshot_isolation=OFF;
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;
BEGIN;
########## innodb_isolation_selects.inc ##########

1
mysql-test/suite/innodb/r/innodb-semi-consistent.result
View File

@ -20,6 +20,7 @@ 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;

1
mysql-test/suite/innodb/r/innodb_bug14007649.result
View File

@ -17,6 +17,7 @@ insert into `t1` (rowid, f1, f2) values (1, 1, 10), (2, 1, NULL);
connect a,localhost,root,,;
connect b,localhost,root,,;
connection a;
set innodb_snapshot_isolation=OFF;
start transaction with consistent snapshot;
connection b;
start transaction;

1
mysql-test/suite/innodb/r/lock_isolation.result
View File

@ -11,6 +11,7 @@ a b
1 1
2 2
connect con_weird,localhost,root;
SET innodb_snapshot_isolation=OFF;
BEGIN;
SELECT * FROM t;
a b