It looks like results of the SCAN query type, both whole query cache and intermediate segment level results, are not cached . Looking at the

getCacheStrategy()

method it doesn't have its own implementation and so is returning null from the default implementation. As a result,

isQueryCacheable()

always returns false for this query type at here. Is there a reason why scan query results are not cached?

sorry, missed this 🧵 at first, but I cannot think of a good reason that caching is not implemented for Scan queries. It's probably just missing an implementation. The main issue to think about would be the potential size of the cached results (Scan query results can be potentially quite large). But, I think that is handled by the caching system generally via the

resultLevelCacheLimit

and

maxEntrySize

parameters in

CacheConfig

Thanks for responding, @Gian Merlino. Is missing implementation the reason for not caching intermediate results on data nodes as well?

yeah, in general the

CacheStrategy

is responsible for both segment-level and result-level caching (although they use different methods). Currently the Scan query has a null

CacheStrategy

(it does not override

getCacheStrategy

in its

ScanQueryQueryToolChest

) so no caching happens anywhere