17.2.5.4 Replication Channel Based Filters

When multiple replication channels exist, for example in a multi-source replication topology, replication filters are applied as follows:

The syntax to create channel specific replication filters extends the existing SQL statements and command options. When a replication channel is not specified the global replication filter is configured to ensure backwards compatibility. The CHANGE REPLICATION FILTER statement supports the FOR CHANNEL clause to configure channel specific filters online. The --replicate-* command options to configure filters can specify a replication channel using the form --replicate-filter_type=channel_name:filter_details. For example, suppose channels channel_1 and channel_2 exist before the server starts, starting the slave with the command line options --replicate-do-db=db1 --replicate-do-db=channel_1:db2 --replicate-do-db=db3 --replicate-ignore-db=db4 --replicate-ignore-db=channel_2:db5 would result in:

To monitor the replication filters in such a setup use the replication_applier_global_filters and replication_applier_filters tables.

The replication filter related command options can take an optional channel followed by a colon, followed by the filter specification. The first colon is interpreted as a separator, subsequent colons are interpreted as literal colons. The following command options support channel specific replication filters using this format:

If you use a colon but do not specify a channel for the filter option, for example --replicate-do-db=:database_id, the option configures the replication filter for the default replication channel. The default replication channel is the replication channel which always exists once replication has been started, and differs from multi-source replication channels which you create manually. When neither the colon nor a channel is specified the option configures the global replication filters, for example --replicate-do-db=database_id configures the global --replicate-do-db filter.

If you configure multiple rewrite-db=from_name->to_name options with the same from_name database, all filters are added together (put into the rewrite_do list) and the first one takes effect.

In addition to the --replicate-* options, replication filters can be configured using the CHANGE REPLICATION FILTER statement. This removes the need to restart the server, but the slave applier thread must be stopped while making the change. To make this statement apply the filter to a specific channel, use the FOR CHANNEL channel clause. For example:

When a FOR CHANNEL clause is provided, the statement acts on the specified channel's replication filters. If multiple types of filters (do_db, do_ignore_table, wild_do_table, and so on) are specified, only the specified filter types are replaced by the statement. In a replication topology with multiple channels, for example on a multi-source replication slave, when no FOR CHANNEL clause is provided, the statement acts on the global replication filters and all channels’ replication filters, using a similar logic as the FOR CHANNEL case. For more information see Section 13.4.2.2, “CHANGE REPLICATION FILTER Syntax”.

When channel specific replication filters have been configured, you can remove the filter by issuing an empty filter type statement. For example to remove all REPLICATE_REWRITE_DB filters from a replication channel named channel_1 issue:

Any REPLICATE_REWRITE_DB filters previously configured, using either command options or CHANGE REPLICATION FILTER, are removed.

The RESET SLAVE ALL statement removes channel specific replication filters that were set on channels deleted by the statement. When the deleted channel or channels are recreated, any global replication filters specified for the slave are copied to them, and no channel specific replication filters are applied.