MDEV-35124 Set innodb_snapshot_isolation=ON by default

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.

mysql-test/suite/innodb/r/deadlock_victim_race.result

@@ -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';

mysql-test/suite/innodb/r/deadlock_wait_lock_race.result

@@ -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';

mysql-test/suite/innodb/r/deadlock_wait_thr_race.result

@@ -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';

mysql-test/suite/innodb/r/innodb-isolation.result

@@ -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 ##########

mysql-test/suite/innodb/r/innodb-semi-consistent.result

@@ -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;

mysql-test/suite/innodb/r/innodb_bug14007649.result

@@ -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;

mysql-test/suite/innodb/r/lock_isolation.result

@@ -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

mysql-test/suite/innodb/t/deadlock_victim_race.test

@@ -27,6 +27,7 @@ SELECT * FROM t WHERE a = 20 FOR UPDATE;
 #             trx 1
 
 --connect(con_2,localhost,root,,)
+SET innodb_snapshot_isolation=OFF;
 # RC is neccessary to do semi-consistent read
 SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
 BEGIN; # trx 2

mysql-test/suite/innodb/t/deadlock_wait_lock_race.test

@@ -34,6 +34,7 @@ SELECT * FROM t WHERE a = 20 FOR UPDATE;
 
 --connect(con_2,localhost,root,,)
 # RC is necessary to do semi-consistent read
+SET innodb_snapshot_isolation=OFF;
 SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
 BEGIN; # trx 2
 # The first time it will be hit on trying to lock (20,20), the second hit

mysql-test/suite/innodb/t/deadlock_wait_thr_race.test

@@ -33,6 +33,7 @@ UPDATE t2 SET a = a + 100;
 SELECT * FROM t WHERE a = 20 FOR UPDATE;
 
 --connect(con_2,localhost,root,,)
+SET innodb_snapshot_isolation=OFF;
 # RC is necessary to do semi-consistent read
 SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
 # It will be hit on trying to lock (20,20).

mysql-test/suite/innodb/t/innodb-isolation.test

@@ -45,6 +45,7 @@ INSERT INTO t2 (SELECT * FROM t1);
 --echo #
 --echo # Do some DML in the default connection and leave the transaction pending.
 --echo #
+SET innodb_snapshot_isolation=OFF;
 SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;
 BEGIN;
 --enable_info
@@ -59,6 +60,7 @@ DELETE FROM t1 WHERE c1 = 6;
 --echo # Connection 1 REPEATABLE READ
 --echo #
 connect (con1,localhost,root,,);
+SET innodb_snapshot_isolation=OFF;
 SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;
 BEGIN;
 --source suite/innodb/include/innodb_isolation_selects.inc

mysql-test/suite/innodb/t/innodb-semi-consistent.test

@@ -28,6 +28,7 @@ connection a;
 commit;
 connection b;
 # perform a semi-consisent read (and unlock non-matching rows)
+set innodb_snapshot_isolation=off;
 set session transaction isolation level read committed;
 update t1 set a=10 where a=5;
 connection a;

mysql-test/suite/innodb/t/innodb_bug14007649.test

@@ -15,6 +15,7 @@ connect (a,localhost,root,,);
 connect (b,localhost,root,,);
 
 connection a;
+set innodb_snapshot_isolation=OFF;
 start transaction with consistent snapshot;
 
 connection b;

mysql-test/suite/innodb/t/lock_isolation.test

@@ -10,6 +10,7 @@ CREATE TABLE t(a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
 INSERT INTO t VALUES (1,1),(2,2);
 BEGIN; SELECT * FROM t LOCK IN SHARE MODE;
 --connect con_weird,localhost,root
+SET innodb_snapshot_isolation=OFF;
 BEGIN;
 SELECT * FROM t;
 --connect consistent,localhost,root