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Kristian Nielsen - MariaDB replication feature preview released
February 24th, 2011
12:11 pm

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MariaDB replication feature preview released

I am pleased to announce the availability of the MariaDB 5.2 feature preview release. Find the details and download links on the knowledgebase.

There has been quite good interest in the replication work I have been doing around MariaDB, and I wanted a way to make it easy for people to use, experiment with, and give feedback on the new features. The result is this replication feature preview release. This will all eventually make it into the next official release, however this is likely still some month off.

All the usual binary packages and source tarballs are available for download. As something new, I now also made apt-enabled repositories available for Debian and Ubuntu; this should greatly simplify installation on these .deb based distributions.

So please try it out, and give feedback on the mailing list or bug tracker. I will make sure to fix any bugs and keep the feature preview updated until everything is available in an official release.

Here is the list of new features in the replication preview release:

Group commit for the binary log

This preview release implements group commit that works when using XtraDB with the binary log enabled. (In previous MariaDB releases, and all MySQL releases at the time of writing, group commit works in InnoDB/XtraDB when the binary log is disabled, but stops working when the binary log is enabled).

Documentation.

Enhancements for START TRANSACTION WITH CONSISTENT SNAPSHOT

START TRANSACTION WITH CONSISTENT SNAPSHOT now also works with the binary log. This means that it is possible to obtain the binlog position corresponding to a transactional snapshot of the database without any blocking of other queries at all. This is used by mysqldump --single-transaction --master-data to do a fully non-blocking backup that can be used to provision a new slave.

START TRANSACTION WITH CONSISTENT SNAPSHOT now also works consistently between transactions involving more than one storage engine (currently XTraDB and PBXT support this).

Documentation.

Annotation of row-based replication events with the original SQL statement

When using row-based replication, the binary log does not contain SQL statements, only discrete single-row insert/update/delete events. This can make it harder to read mysqlbinlog output and understand where in an application a given event may have originated, complicating analysis and debugging.

This feature adds an option to include the original SQL statement as a comment in the binary log (and shown in mysqlbinlog output) for row-based replication events.

Documentation.

Row-based replication for tables with no primary key

This feature can improve the performance of row-based replication on tables that do not have a primary key (or other unique key), but that do have another index that can help locate rows to update or delete. With this feature, index cardinality information from ANALYZE TABLE is considered when selecting the index to use (before this feature is implemented, the first index was selected unconditionally).

Documentation.

Early release during prepare phase of XtraDB row locks

This feature adds an option to make XtraDB release the row locks for a transaction earlier during the COMMIT step when running with --sync-binlog=1 and --innodb-flush-log-at-trx-commit=1. This can improve throughput if the workload has a bottleneck on hot-spot rows.

Documentation.

PBXT consistent commit ordering

This feature implements the new commit ordering storage engine API in PBXT. With this feature, it is possible to use START TRANSACTION WITH CONSISTENT SNAPSHOT and get consistency among transactions that involve both XtraDB and InnoDB. (Without this feature, there is no such consistency guarantee. For example, even after running START TRANSACTION WITH CONSISTENT SNAPSHOT it was still possible for the InnoDB/XtraDB part of some transaction T to be visible and the PBXT part of the same transaction T to not be visible.)

Documentation.

Miscellaneous

  • Small change to make mysqlbinlog omit redundant use statements around BEGIN/SAVEPOINT/COMMIT/ROLLBACK events when reading MySQL 5.0 binlogs.

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