Redis Object Cache for WordPress

Redis object cache needs a running Redis server, a compatible PHP client and a WordPress cache integration; the plugin alone cannot supply the server. Confirm all three before enabling the persistent cache.

• Redis service: reachable over a local socket or a protected connection.
• PHP client: PhpRedis for the site's PHP version, or the plugin's supported Predis client.
• WordPress integration: Redis Object Cache, or one alternative object-cache implementation, not competing drop-ins.
• Administration access: permission to install server packages and restart services, unless the host has already provisioned them.
• Memory budget: a dedicated cache allocation that leaves enough RAM for PHP and the database.

The Redis Object Cache maintainer documentation confirms the clients, constants and WP-CLI commands. A typical shared account cannot install its own daemon; a Linux VPS gives an administrator the necessary control.

Install Redis Object Cache, define its connection settings before WordPress loads, then enable its object-cache drop-in. Back up wp-config.php first and disable any competing object-cache feature.

1. Confirm Redis is reachable from the site's PHP environment.
2. Install and activate Redis Object Cache through Plugins → Add New.
3. Add the required constants above the stop-editing line in wp-config.php.
4. Open Settings → Redis and choose Enable Object Cache.
5. Confirm Connected, then browse representative public and logged-in pages.

define( 'WP_REDIS_HOST', '127.0.0.1' );
define( 'WP_REDIS_PORT', 6379 );
define( 'WP_REDIS_PREFIX', 'shop1_' );
define( 'WP_REDIS_DATABASE', 0 );

A prefix prevents naming collisions; it is not a security boundary. Give each independent site's disposable cache its own logical database or instance where appropriate. A database-wide flush can affect every site's keys in that database even when their prefixes differ.

For an existing Unix socket, use its actual path and permissions instead of TCP:

define( 'WP_REDIS_SCHEME', 'unix' );
define( 'WP_REDIS_PATH', '/var/run/redis/redis-server.sock' );

Use either TCP or socket settings to match the deployment, not an invented socket path. With WP-CLI, run these from the WordPress installation as its authorised site user:

wp plugin install redis-cache --activate
wp redis enable
wp redis status

Redis object cache is most useful when repeated object lookups contribute to slow dynamic requests, not when images or an external API dominate the delay. Choose it after identifying the bottleneck.

WooCommerce carts, account areas, membership pages and wp-admin commonly bypass a public page cache. A persistent object backend can help those requests reuse suitable data, but checkout still needs correct application logic and database writes. Never cache another customer's personalised page as public HTML.

A small page-cached brochure site may gain little. Measure first, then decide whether the added service, memory and operational work are justified. WooCommerce hosting addresses the hosting environment; Redis is one component rather than a substitute for the rest of the stack.

Keep one object-cache integration active, document its recovery switch and include it in migration testing. A server move changes connection details even when the WordPress files have been copied correctly.