Clarify L2 cache vs. cache preload: payload size vs. call count - #185
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Clarify L2 cache vs. cache preload: payload size vs. call count#185EclipseEternal wants to merge 1 commit into
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The L2 cache section described L2 caching as reducing "network traffic" without distinguishing that from reducing the number of remote cache calls. L2 caching still checks the remote cache on every read to validate its local copy - what shrinks is the payload of each call (a hash instead of the full value), not the number of round trips. The cache preload paragraph already pointed at the preload feature but described its benefit only as "decreases the pressure on Redis," without stating that it is an independent mechanism (usable with or without L2) and that it is specifically the round-trip-count reducer, via pipelining a fixed list of IDs into one batch.
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Description
The L2 cache configuration page describes L2 caching as reducing "network traffic" without distinguishing that from reducing the number of remote cache calls. In the legacy
RemoteSynchronizedCacheimplementation, each web node still calls the remote cache on every read to validate its local copy (a hash comparison) - so L2 caching does not reduce the number of round trips to the remote cache. What it reduces is the size of each round trip: a short hash instead of the full cached value, unless the local copy is stale.Separately, the page already recommends the
cache preloadfeature but only describes its benefit as "decreases the pressure on Redis," without stating that:This PR rewords both passages to make the size-vs-count distinction explicit, so a reader looking to reduce the number of Redis calls is pointed at cache preload rather than L2 caching.
Changes
help/configuration/cache/level-two-cache.md: two paragraphs reworded (no structural changes, no other content touched).