16.2.2.3 Startup Options and Replication Channels

This section describes startup options which are impacted by the addition of replication channels.

The following startup settings must be configured correctly to use multi-source replication.

relay_log_info_repository.

This must be set to TABLE. If this variable is set to FILE, attempting to add more sources to a replica fails with .
master_info_repository

This must be set to TABLE. If this variable is set to FILE, attempting to add more sources to a replica fails with .

The following startup options now affect all channels in a replication topology.

--log-slave-updates

All transactions received by the replica (even from multiple sources) are written in the binary log.
--relay-log-purge

When set, each channel purges its own relay log automatically.
--slave_transaction_retries

Applier threads of all channels retry transactions.
--skip-slave-start

No replication threads start on any channels.
--slave-skip-errors

Execution continues and errors are skipped for all channels.

The values set for the following startup options apply on each channel; since these are mysqld startup options, they are applied on every channel.

--max-relay-log-size=size

Maximum size of the individual relay log file for each channel; after reaching this limit, the file is rotated.
--relay-log-space-limit=size

Upper limit for the total size of all relay logs combined, for each individual channel. For N channels, the combined size of these logs is limited to relay_log_space_limit * N.
--slave-parallel-workers=value

Number of worker threads per channel.
slave_checkpoint_group

Waiting time by an I/O thread for each source.
--relay-log-index=filename

Base name for each channel's relay log index file. See Section 16.2.2.4, “Replication Channel Naming Conventions”.
--relay-log=filename

Denotes the base name of each channel's relay log file. See Section 16.2.2.4, “Replication Channel Naming Conventions”.
--slave_net-timeout=N

This value is set per channel, so that each channel waits for N seconds to check for a broken connection.
--slave-skip-counter=N

This value is set per channel, so that each channel skips N events from its source.