3.6 added lookup tables, which is WooCommerce admitting postmeta does not scale. What they contain, what they do not, and the regeneration nobody schedules.
Changing the shape of a cached value makes every existing entry wrong, and there is no way to clear them selectively without knowing every key that exists. A…
Caching what a query returned saves the round trip and leaves the hydration, the mapping and the aggregation to happen on every request anyway. Profiling usually shows the…
A thousand cache entries written during a deploy with the same TTL expire in the same second, and the stampede recurs on a fixed interval forever. Deriving the…
Caching the rows a query returned saves the database round trip and leaves the hydration, the mapping and the aggregation to happen on every request anyway. Profiling usually…
An expensive cached value expires under load and every concurrent request misses simultaneously, so forty requests all run the same four-second query at once and the database falls…
The object cache is per-request by default and persistent with a drop-in, and either way the cache group is what keeps two plugins from using the same key…