Moodle Universal Cache (MUC)

Caching stores frequently accessed data in transient storage and expedites its access using a cached copy instead of prefetched (from disk) or recomputed (in memory) data.

Note

Caching has proven to be one of the most efficient performance optimization techniques, and Moodle is no exception.

Moodle contains a powerful caching framework called MUC, which allows certain functions to take advantage of different configured caching services (docs.moodle.org/en/Caching).

Understanding MUC

Before we look at how MUC works, let’s explore some basic concepts: cache types (modes), cache stores, and cache definitions. The following diagram shows all three concepts and how they work together in MUC:

Figure 15.6 – Moodle Universal Cache

Moodle has nearly 100 cache definitions—for example, fetching of language strings, config settings, or processed CSS. Cache definitions are mapped onto cache stores, which act...