@@ -103,19 +103,21 @@ features of GitLab work with MySQL/MariaDB:
...
@@ -103,19 +103,21 @@ features of GitLab work with MySQL/MariaDB:
1. MySQL support for subgroups was [dropped with GitLab 9.3][post].
1. MySQL support for subgroups was [dropped with GitLab 9.3][post].
See [issue #30472][30472] for more information.
See [issue #30472][30472] for more information.
1. GitLab Geo does [not support MySQL](https://docs.gitlab.com/ee/gitlab-geo/database.html#mysql-replication).
1. Geo **[STARTER ONLY]** does [not support MySQL](https://docs.gitlab.com/ee/gitlab-geo/database.html#mysql-replication). This means no supported Disaster Recovery solution if using MySQL.
1.[Zero downtime migrations][zero] do not work with MySQL
1.[Zero downtime migrations][../update/README.md#upgrading-without-downtime] do not work with MySQL.
1. GitLab [optimizes the loading of dashboard events](https://gitlab.com/gitlab-org/gitlab-ce/issues/31806) using [PostgreSQL LATERAL JOINs](https://blog.heapanalytics.com/postgresqls-powerful-new-join-type-lateral/).
1. GitLab [optimizes the loading of dashboard events](https://gitlab.com/gitlab-org/gitlab-ce/issues/31806) using [PostgreSQL LATERAL JOINs](https://blog.heapanalytics.com/postgresqls-powerful-new-join-type-lateral/).
1. In general, SQL optimized for PostgreSQL may run much slower in MySQL due to
1. In general, SQL optimized for PostgreSQL may run much slower in MySQL due to
differences in query planners. For example, subqueries that work well in PostgreSQL
differences in query planners. For example, subqueries that work well in PostgreSQL
may not be [performant in MySQL](https://dev.mysql.com/doc/refman/5.7/en/optimizing-subqueries.html)
may not be [performant in MySQL](https://dev.mysql.com/doc/refman/5.7/en/optimizing-subqueries.html).
1. Binary column index length is limited to 20 bytes. This is accomplished with [a hack](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/config/initializers/mysql_set_length_for_binary_indexes.rb).
1. MySQL requires a variety of hacks to increase limits on various columns, [for example](https://gitlab.com/gitlab-org/gitlab-ce/issues/49583).
1.[The milestone filter runs slower queries on MySQL](https://gitlab.com/gitlab-org/gitlab-ce/issues/51173#note_99391731).
1. We expect this list to grow over time.
1. We expect this list to grow over time.
Existing users using GitLab with MySQL/MariaDB are advised to
Existing users using GitLab with MySQL/MariaDB are advised to
[migrate to PostgreSQL](../update/mysql_to_postgresql.md) instead.
[migrate to PostgreSQL](../update/mysql_to_postgresql.md) instead.
