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MySQL 8.0 Reference Manual
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17.2.2.3 Startup Options and Replication Channels

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

Themaster_info_repositoryandrelay_log_info_repositorysystem variables mustnotbe set toFILEwhen you use replication channels. In MySQL 8.0, theFILEsetting is deprecated, andTABLEis the default, so the system variables can be omitted. From MySQL 8.0.23, they must be omitted because their use is deprecated from that release. If these system variables are set toFILE, attempting to add more sources to a replica fails withER_SLAVE_NEW_CHANNEL_WRONG_REPOSITORY.

The following startup options now affectallchannels in a replication topology.

The values set for the following startup options apply on each channel; since these aremysqldstartup 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. ForNchannels, the combined size of these logs is limited torelay_log_space_limit *N.

  • --slave-parallel-workers=value

    Number of replication applier 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. SeeSection 17.2.2.4, “Replication Channel Naming Conventions”.

  • --relay-log=filename

    Denotes the base name of each channel's relay log file. SeeSection 17.2.2.4, “Replication Channel Naming Conventions”.

  • --slave_net-timeout=N

    This value is set per channel, so that each channel waits forNseconds to check for a broken connection.

  • --slave-skip-counter=N

    This value is set per channel, so that each channel skipsNevents from its source.