Added a new close_connection_after_refresh metadata_cache option to control whether a connection remains open for future metadata refresh operations. If set to 0 (default), the metadata_cache keeps the connection open if the refresh succeeded and if the next refresh is to the same MySQL server. Setting it to 1 is similar to previous behavior, in that the connection is closed after each metadata refresh operation. (WL #16652)

The destinations option now supports Unix domain sockets. (WL #16582)

This release introduces Routing Guidelines, a flexible and unified configuration interface enabling users to customize routing behavior. Routing Guidelines are defined as a JSON document, stored in the metadata schema.

Use the MySQL Shell AdminAPI RoutingGuideline class to interact with these guidelines, and see the MySQL Shell 9.2.0 release notes for additional information. (WL #14119)

Important Change: MySQL Router no longer supports MySQL Server versions from a newer series. The metadata is checked and discarded for servers from a newer series, a check that executes during bootstrap and during periodic metadata refresh operations. A newer version in the same series is supported. For example, MySQL Router 8.4.4 supports MySQL Server 8.4.5 but not MySQL Server 9.0.0. (Bug #36041256)

Because building with CMAKE_BUILD_TYPE=Debug disables optimizations, std::vector.resize() attempted to initialize every byte before each read from an encrypted socket. Memory usage was improved to account for this. (Bug #37385923)

Accessing the /routes/{name}/connections REST API endpoint while also benchmarking queries through the router could cause the router to unexpectedly halt. (Bug #37251508)

OpenID Connect authentication stopped functioning for a connection with the following scenario: the default authentication plugin was set to openid_connect, the MySQL Router connection pool was enabled, and the connection was in the pool ready for reuse. (Bug #37190332)

When stats_updates_frequency was set to an unexpected value, MySQL Router would log a warning during each metadata refresh thus clogging the logs. Now the warning is logged just once, unless the value changed. (Bug #116951, Bug #37391164)