Hi SOLR Community, I have a question about cache implementations based on some seemingly inconsistent documentation I'm looking at. I'm currently inquiring about 8.3, but more generally about solr version 8 too for upgrade planning.
In the description in the docs for cache implementations says <https://lucene.apache.org/solr/guide/8_3/query-settings-in-solrconfig.html#cache-implementations> [The caffeine] cache implementation is recommended over other legacy caches as it usually offers [good stuff]. On the other hand, down in the actual filter cache section says The filter cache uses a specialized cache named as FastLRUCache which is optimized for fast concurrent access with the trade-off that writes and evictions are costlier than the LRUCache used for query result cache and document cache. This implies the FastLRU cache is the only option as the documentation doesn't say "defaults to a specialized cache" but rather states it in a way to imply necessity. Even if we assume that was not intended, it does imply that the FastLRU cache is the only one suited to the Filter Cache. Further, the documentation in the SOLR config says yet another thing, that you can use FastLRU or LRU only <https://github.com/apache/lucene-solr/blob/branch_8_8/solr/server/solr/configsets/sample_techproducts_configs/conf/solrconfig.xml> class - the SolrCache implementation LRUCache or (LRUCache or FastLRUCache) Can you help me untangle this to understand the following: (a) At what version did the caffeine cache reach production stability? (b) Is the caffeine cache, and really all implementations, able to be used on any cache, or are the restrictions about which cache implementations may be used for which cache? If the latter, can you provide some guidance? Disclaimer: I'm not asking which caches will be fastest for my applications. I know that you can't know that ;) Rather, I want to be sure which production version reached production stability (esp. for the filter cache). Thanks! Stephen
