MDEV-21921 Make transaction_isolation and transaction_read_only into system variables

In MariaDB, we have a confusing problem where:
* The transaction_isolation option can be set in a configuration file, but it cannot be set dynamically.
* The tx_isolation system variable can be set dynamically, but it cannot be set in a configuration file.

Therefore, we have two different names for the same thing in different contexts. This is needlessly confusing, and it complicates the documentation. The same thing applys for transaction_read_only.

MySQL 5.7 solved this problem by making them into system variables. https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-20.html

This commit takes a similar approach by adding new system variables and marking the original ones as deprecated. This commit also resolves some legacy problems related to SET STATEMENT and transaction_isolation.

mysql-test/suite/innodb_zip/r/bug56680.result

@@ -1,4 +1,4 @@
-SET GLOBAL tx_isolation='REPEATABLE-READ';
+SET GLOBAL transaction_isolation='REPEATABLE-READ';
 CREATE TABLE bug56680(
 a INT AUTO_INCREMENT PRIMARY KEY,
 b CHAR(1),
@@ -28,7 +28,7 @@ connection default;
 SELECT b FROM bug56680;
 b
 x
-SET GLOBAL tx_isolation='READ-UNCOMMITTED';
+SET GLOBAL transaction_isolation='READ-UNCOMMITTED';
 INSERT INTO bug56680 SELECT 0,b,c FROM bug56680;
 INSERT INTO bug56680 SELECT 0,b,c FROM bug56680;
 INSERT INTO bug56680 SELECT 0,b,c FROM bug56680;

mysql-test/suite/innodb_zip/r/index_large_prefix.result

@@ -10,8 +10,8 @@ show warnings;
 Level	Code	Message
 begin;
 update worklog5743 set a = (repeat("x", 17000));
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 connect  con1,localhost,root,,;
 select a = repeat("x", 17000) from worklog5743;
@@ -22,8 +22,8 @@ a = repeat("b", 16000)
 1
 connect  con2,localhost,root,,;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a = repeat("x", 17000) from worklog5743;
 a = repeat("x", 17000)
@@ -42,8 +42,8 @@ insert into worklog5743 values(9, repeat("a", 10000));
 begin;
 update worklog5743 set a1 = 1000;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -53,8 +53,8 @@ a1	a2 = repeat("a", 10000)
 9	1
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 a1	a2 = repeat("a", 10000)
@@ -68,8 +68,8 @@ insert into worklog5743 values(9, repeat("a", 10000));
 begin;
 update worklog5743 set a1 = 1000;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -79,8 +79,8 @@ a1	a2 = repeat("a", 10000)
 9	1
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 a1	a2 = repeat("a", 10000)
@@ -258,8 +258,8 @@ select a1, left(a2, 20) from worklog5743_16;
 a1	left(a2, 20)
 1000	aaaaaaaaaaaaaaaaaaaa
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, left(a2, 20) from worklog5743_1 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -293,8 +293,8 @@ a1	left(a2, 20)
 9	aaaaaaaaaaaaaaaaaaaa
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, left(a2, 20) from worklog5743_1 where a1 = 9;
 a1	left(a2, 20)
@@ -367,8 +367,8 @@ repeat("a", 3068));
 begin;
 update worklog5743 set a1 = 1000;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1 from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -378,8 +378,8 @@ a1
 9
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1 from worklog5743 where a1 = 9;
 a1
@@ -399,8 +399,8 @@ insert into worklog5743 values(repeat("a", 20000));
 begin;
 insert into worklog5743 values(repeat("b", 20000));
 update worklog5743 set a = (repeat("x", 25000));
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 connection con1;
 select a = repeat("a", 20000) from worklog5743;
@@ -409,8 +409,8 @@ a = repeat("a", 20000)
 disconnect con1;
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a = repeat("x", 25000) from worklog5743;
 a = repeat("x", 25000)

mysql-test/suite/innodb_zip/r/index_large_prefix_4k.result

@@ -13,8 +13,8 @@ Level	Code	Message
 SET sql_mode= default;
 begin;
 update worklog5743 set a = (repeat("x", 17000));
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 connect  con1,localhost,root,,;
 select a = repeat("x", 17000) from worklog5743;
@@ -25,8 +25,8 @@ a = repeat("b", 16000)
 1
 connect  con2,localhost,root,,;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a = repeat("x", 17000) from worklog5743;
 a = repeat("x", 17000)
@@ -45,8 +45,8 @@ insert into worklog5743 values(9, repeat("a", 10000));
 begin;
 update worklog5743 set a1 = 1111;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -56,8 +56,8 @@ a1	a2 = repeat("a", 10000)
 9	1
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 a1	a2 = repeat("a", 10000)
@@ -71,8 +71,8 @@ insert into worklog5743 values(9, repeat("a", 10000));
 begin;
 update worklog5743 set a1 = 2222;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -82,8 +82,8 @@ a1	a2 = repeat("a", 10000)
 9	1
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 a1	a2 = repeat("a", 10000)
@@ -183,8 +183,8 @@ select a1, left(a2, 20) from worklog5743_4;
 a1	left(a2, 20)
 1000	aaaaaaaaaaaaaaaaaaaa
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, left(a2, 20) from worklog5743_1 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -206,8 +206,8 @@ a1	left(a2, 20)
 9	aaaaaaaaaaaaaaaaaaaa
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, left(a2, 20) from worklog5743_1 where a1 = 9;
 a1	left(a2, 20)
@@ -261,8 +261,8 @@ insert into worklog5743 values(9, repeat("a", 764));
 begin;
 update worklog5743 set a1 = 4444;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1 from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -272,8 +272,8 @@ a1
 9
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1 from worklog5743 where a1 = 9;
 a1
@@ -289,8 +289,8 @@ insert into worklog5743 values(repeat("a", 20000));
 begin;
 insert into worklog5743 values(repeat("b", 20000));
 update worklog5743 set a = (repeat("x", 25000));
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 connection con1;
 select a = repeat("a", 20000) from worklog5743;
@@ -299,8 +299,8 @@ a = repeat("a", 20000)
 disconnect con1;
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a = repeat("x", 25000) from worklog5743;
 a = repeat("x", 25000)

mysql-test/suite/innodb_zip/r/index_large_prefix_8k.result

@@ -16,8 +16,8 @@ Note	1071	Specified key was too long; max key length is 1536 bytes
 SET sql_mode= default;
 begin;
 update worklog5743 set a = (repeat("x", 17000));
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 connect  con1,localhost,root,,;
 select a = repeat("x", 17000) from worklog5743;
@@ -28,8 +28,8 @@ a = repeat("b", 16000)
 1
 connect  con2,localhost,root,,;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a = repeat("x", 17000) from worklog5743;
 a = repeat("x", 17000)
@@ -48,8 +48,8 @@ insert into worklog5743 values(9, repeat("a", 10000));
 begin;
 update worklog5743 set a1 = 1000;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -59,8 +59,8 @@ a1	a2 = repeat("a", 10000)
 9	1
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 a1	a2 = repeat("a", 10000)
@@ -74,8 +74,8 @@ insert into worklog5743 values(9, repeat("a", 10000));
 begin;
 update worklog5743 set a1 = 1000;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -85,8 +85,8 @@ a1	a2 = repeat("a", 10000)
 9	1
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, a2 = repeat("a", 10000) from worklog5743 where a1 = 9;
 a1	a2 = repeat("a", 10000)
@@ -217,8 +217,8 @@ select a1, left(a2, 20) from worklog5743_8;
 a1	left(a2, 20)
 1000	aaaaaaaaaaaaaaaaaaaa
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1, left(a2, 20) from worklog5743_1 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -246,8 +246,8 @@ a1	left(a2, 20)
 9	aaaaaaaaaaaaaaaaaaaa
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1, left(a2, 20) from worklog5743_1 where a1 = 9;
 a1	left(a2, 20)
@@ -295,8 +295,8 @@ update worklog5743 set a1 = 1000;
 begin;
 update worklog5743 set a1 = 1000;
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 explain select a1 from worklog5743 where a1 = 9;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -305,8 +305,8 @@ select a1 from worklog5743 where a1 = 9;
 a1
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a1 from worklog5743 where a1 = 9;
 a1
@@ -325,8 +325,8 @@ insert into worklog5743 values(repeat("a", 20000));
 begin;
 insert into worklog5743 values(repeat("b", 20000));
 update worklog5743 set a = (repeat("x", 25000));
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 connection con1;
 select a = repeat("a", 20000) from worklog5743;
@@ -335,8 +335,8 @@ a = repeat("a", 20000)
 disconnect con1;
 connection con2;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 select a = repeat("x", 25000) from worklog5743;
 a = repeat("x", 25000)

mysql-test/suite/innodb_zip/r/prefix_index_liftedlimit.result

@@ -793,16 +793,16 @@ col_1_text = REPEAT("a", 200)	col_2_text  = REPEAT("o", 200)
 1	1
 0	1
 connection con1;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 REPEATABLE-READ
 SELECT col_1_text = REPEAT("b", 200) , col_2_text = REPEAT("o", 200) FROM
 worklog5743;
 col_1_text = REPEAT("b", 200)	col_2_text = REPEAT("o", 200)
 0	1
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 SELECT col_1_text = REPEAT("b", 200) , col_2_text = REPEAT("o", 200) FROM
 worklog5743;
@@ -864,8 +864,8 @@ col_1_text = REPEAT("a", 200)	col_2_text  = REPEAT("o", 200)
 COMMIT;
 connection con1;
 SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
-select @@session.tx_isolation;
-@@session.tx_isolation
+select @@session.transaction_isolation;
+@@session.transaction_isolation
 READ-UNCOMMITTED
 SELECT col_1_text = REPEAT("b", 200) , col_2_text = REPEAT("o", 200) FROM
 worklog5743;