Release announcement 2.0.6

The maintenance release 2.0.6 fixes a crash occurring when a new column is added on the source database with the default value NOW().

The maintenance introduced in the version 2.0.5 is now less aggressive. In particular the run_maintenance command now executes a conventional VACUUM on the source’s log tables, unless the switch --full is specified. In that case a VACUUM FULL is executed. The detach has been disabled and may be completely removed in the future releases because very fragile and prone to errors.

However running VACUUM FULL on the log tables can cause the other sources to be blocked during the maintenance run.

This release adds an optional parameter on_error_read: on the mysql type’s sources which allow the read process to stay up if the mysql database is refusing connections (e.g. MySQL down for maintenance). Following the principle of least astonishment the parameter if omitted doesn’t cause any change of behaviour. If added with the value continue (e.g. on_error_read: continue) will prevent the replica process to stop in the case of connection issues from the MySQL database with a warning is emitted on the replica log .

This release adds the support for mysql 5.5 which doesn’t have the parameter binlog_row_image.

enable_replica now can reset the replica status to stopped even if the catalogue version is mismatched. This simplifies the upgrade procedure in case of errored or wrongly running replicas.

As this change requires a replica catalogue upgrade is very important to follow the upgrade instructions provided below.

• If working via ssh is suggested to open a screen session
• Before upgrading pg_chameleon stop all the replica processes.
• Upgrade the pg_chameleon package with pip install pg_chameleon --upgrade
• Upgrade the replica schema with the command chameleon upgrade_replica_schema --config <your_config>
• Start the replica processes

If the upgrade procedure refuses to upgrade the catalogue because of running or errored replicas is possible to reset the statuses with the enable_replica command.

If the catalogue upgrade is still not possible downgrading pgchameleon to the version 2.0.5 with pip install pg_chameleon==2.0.5 should make the replicas startable again.

Changelog from v2.0.5

• fix for issue #69 add source’s optional parameter on_error_read: to allow the read process to continue in case of connection issues with the source database (e.g. MySQL in maintenance)
• remove the detach partition during the maintenance process as this proved to be a very fragile approach
• add switch --full to run a VACUUM FULL during the maintenance
• when running the maintentenance execute a VACUUM instead of a VACUUM FULL
• fix for issue #68. fallback to binlog_row_image=FULL if the parameter is missing in mysql 5.5.
• add cleanup for default value NOW() when adding a new column with ALTER TABLE
• allow enable_replica to reset the source status in the case of a catalogue version mismatch