Documentation Home
MySQL 8.0 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 37.7Mb
PDF (A4) - 37.7Mb
PDF (RPM) - 33.8Mb
HTML Download (TGZ) - 8.3Mb
HTML Download (Zip) - 8.4Mb
HTML Download (RPM) - 7.3Mb
Man Pages (TGZ) - 130.0Kb
Man Pages (Zip) - 185.6Kb
Info (Gzip) - 3.3Mb
Info (Zip) - 3.3Mb


MySQL 8.0 Reference Manual  /  ...  /  Deploying in Multi-Primary or Single-Primary Mode

Pre-General Availability Draft: 2018-02-22

21.4.1 Deploying in Multi-Primary or Single-Primary Mode

Group Replication operates in the following different modes:

  • single-primary mode

  • multi-primary mode

The default mode is single-primary. It is not possible to have members of the group deployed in different modes, for example one configured in multi-primary mode while another one is in single-primary mode. To switch between modes, the group and not the server, needs to be restarted with a different operating configuration. Regardless of the deployed mode, Group Replication does not handle client-side fail-over, that must be handled by the application itself, a connector or a middleware framework such as a proxy or router.

When deployed in multi-primary mode, statements are checked to ensure they are compatible with the mode. The following checks are made when Group Replication is deployed in multi-primary mode:

  • If a transaction is executed under the SERIALIZABLE isolation level, then its commit fails when synchronizing itself with the group.

  • If a transaction executes against a table that has foreign keys with cascading constraints, then the transaction fails to commit when synchronizing itself with the group.

These checks can be deactivated by setting the option group_replication_enforce_update_everywhere_checks to FALSE. When deploying in single-primary mode, this option must be set to FALSE.


User Comments
Sign Up Login You must be logged in to post a comment.