kim.pepper's sandbox: Replica Cache

This module provides a replica database cache backend.

Cache gets will attempt to use the replica database connection if available. Otherwise, the primary database will be used as normal.

Cache sets will trigger the 'replica kill switch' forcing the primary database to be used for the remainder of the current request.

Setup

Specify the cache backend in settings.php:

$settings['cache']['default'] = 'cache.backend.replica';

Configuration

You may wish to adjust the maximum_replication_lag setting from it's default of
300 seconds.

$settings['maximum_replication_lag'] = 5;