Expands on which queries are cacheable in RC (#9393)

* expand on which queries are cacheable in RC

Signed-off-by: Peter Alfonsi <petealft@amazon.com>

* Update _search-plugins/caching/request-cache.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Signed-off-by: Peter Alfonsi <peter.alfonsi@gmail.com>

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Signed-off-by: Peter Alfonsi <petealft@amazon.com>
Signed-off-by: Peter Alfonsi <peter.alfonsi@gmail.com>
Co-authored-by: Peter Alfonsi <petealft@amazon.com>
Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

Author: 3 people

_search-plugins/caching/request-cache.md

@@ -12,7 +12,7 @@ The OpenSearch index request cache is a specialized caching mechanism designed t
 
 The cache is automatically invalidated at the configured refresh interval. The invalidation includes document updates (including document deletions) and changes to index settings. This ensures that stale results are never returned from the cache. When the cache size exceeds its configured limit, the least recently used entries are evicted to make room for new entries.
 
-Search requests with `size=0` are cached in the request cache by default. Search requests with non-deterministic characteristics (such as `Math.random()`) or relative times (such as `now` or `new Date()`) are ineligible for caching.
+Some queries are ineligible for the request cache. These include profiled queries, scroll queries, and search requests with non-deterministic characteristics (such as those using `Math.random()` or DFS queries) or relative times (such as `now` or `new Date()`). By default, only requests with `size=0` are cacheable. In OpenSearch 2.19 and later, this behavior can be changed using `indices.requests.cache.maximum_cacheable_size`.
 {: .note}
 
 ## Configuring request caching