Chapter 18. Caching Strategy to Ensure WordPress Scales


  • Understanding caching

  • Using WordPress caching mechanisms

  • Optimizing PHP with opcode caching

  • Caching MySQL with HyperDB and the query cache

  • Harnessing the "cloud"

One big complaint from bloggers who have highly trafficked blogs is that WordPress doesn't scale. In fact, if you visit social networking sites like, you will undoubtedly find people who talk about WordPress as being poorly written software that won't last online.

Out of the box, WordPress is effective for probably 99 percent of blogs with no additional work required. However, with a good, sound caching strategy, you can ensure that WordPress can scale to handle increasingly large amounts of traffic.

Typically, when looking at WordPress scaling requirements for clients, I consider three primary levels of caching: the software layer (WordPress), the core software layer (PHP and MySQL), and the infrastructure level (server hardware and network layout).

Implementing solutions in some or all of these caching "zones" may be enough to keep everything ticking along smoothly. But if you fail to put effective caching mechanisms into place before trying to sustain a major influx in traffic, you could encounter significant headaches down the road.

Understanding Caching

Caching is one of those things that is clear to most people on a conceptual level, but the actual nuts and bolts tend to be a bit evasive. In its simplest form, caching is a mechanism by which data ...

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