tx_isolation is a strange name, I agree with GeoffMontee, better to create @@transaction_isolation sysvar, like MySQL did.
We can mark tx_isolation deprecated and remove it eventually.
ralf.gebhardt@mariadb.com, no, I would consider it backward compatibility 
btw, mysql java driver set transaction_isolation when creating connection, making java connector incompatible with MariaDB:
see https://github.com/mysql/mysql-connector-j/blob/release/8.0/src/main/user-impl/java/com/mysql/cj/jdbc/ConnectionImpl.java#L1211
resulting in error like this one :
java.sql.SQLException: Unknown system variable 'transaction_isolation' |
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) |
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) |
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:829) |
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:449) |
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:242) |
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) |
at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677) |
at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:251) |
at test.Test.main(Test.java:15) |
mysql ODBC use it as well, but only to retrieve isolation level: https://github.com/mysql/mysql-connector-odbc/blob/7f85d3d3e59c30c754570b1a1b47df4b5737e6e2/test/my_tran.c
Hi all! This is my first attempt to create a patch to MariaDB community. https://github.com/MariaDB/server/pull/2491
To implement this feature, I mostly backport the code from MySQL 5.7 branch, noted here. It adds 2 new system variables (transaction_isolation and transaction_read_only) which references the same field as the original variables (tx_isolation and tx_read_only). The original variables are marked as deprecated, and users will get a warning when setting the original variables.
To avoid "surprises" to mariadb developers, I kept the internal representation of these variables. In other words, the change is only visible from a user's perspective. I also updated all the variables referenced in the tests for consistency.
@serg @nikitamalyavin What do you think about this approach and the PR? Thanks in advance.
Thank you very much Junqi Xie
Thanks junqi_xie for documenting the changes. Note that I reverted and will rework the SET TRANSACTION changes at https://mariadb.com/kb/en/set-transaction/+revision/125221/125173/, as the Knowledge Base is for all maintained versions, currently 10.3+, and the new instructions you specified will not work on releases prior to 11.1