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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.
This commit is contained in:
Junqi Xie
2023-03-12 13:55:30 +08:00
committed by Daniel Black
parent 4472a7b4ff
commit d20a96f9c1
100 changed files with 1232 additions and 962 deletions

View File

@@ -40,7 +40,7 @@ connection con1;
SET GLOBAL TRANSACTION ISOLATION LEVEL REPEATABLE READ;
SELECT @@tx_isolation;
SELECT @@transaction_isolation;
# Record count should be 1
SELECT COUNT(*) FROM tab;
@@ -54,7 +54,7 @@ connection con2;
SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;
SELECT @@tx_isolation;
SELECT @@transaction_isolation;
START TRANSACTION;
@@ -155,7 +155,7 @@ connection con1;
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;
SELECT @@tx_isolation;
SELECT @@transaction_isolation;
# Record count should be 1
SELECT COUNT(*) FROM tab;
@@ -169,7 +169,7 @@ connection con2;
SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED;
SELECT @@tx_isolation;
SELECT @@transaction_isolation;
START TRANSACTION;