Cache Tools Overview

Overview

WordPress has a built-in object cache layer that stores temporary data in memory or an external cache backend (Redis, Memcached). WP-CLI's wp cache commands give you direct read/write/flush access to this cache from the terminal.

WordPress Cache Architecture

WordPress Request
     │
     ▼
Object Cache Layer (wp_cache_get / wp_cache_set)
     │
     ├── Default: WP_Object_Cache (in-memory, per-request only)
     │
     └── Persistent: Redis / Memcached (survives across requests)

When the Object Cache Matters

Event	Action Needed
After wp search-replace	wp cache flush
After wp import	wp cache flush
After plugin activate/deactivate	wp cache flush
After wp option update	Usually auto-cleared, but flush if stale
Debugging stale data	wp cache get KEY GROUP to inspect

wp cache Subcommands at a Glance

Command	Purpose
wp cache type	Identify which cache backend is active
wp cache flush	Clear all cached data
wp cache get	Read a specific cached value
wp cache set	Write a value to the cache
wp cache add	Write only if key does not exist
wp cache delete	Remove a specific cache key

Key Concepts

• Groups — Cache is namespaced by group (e.g., posts, users, options). Always specify the correct group when targeting a specific key.
• Expiration — Cache entries have a TTL in seconds. 0 means no expiration (backend-dependent).
• Persistent vs non-persistent — Without a persistent cache plugin (Redis/Memcached), wp cache flush has no effect on the next real request — the in-memory cache is request-scoped.

Next Steps

• wp cache flush — the most commonly used cache command.
• wp cache type — check if Redis or Memcached is active.