Solr Filters: Caching vs Post-Filtering

Solr Filters: Caching vs Post-Filtering

A while back, I joined the #solr IRC channel in the middle of conversation about Solr's queryResultCache & filterCache. The first message I saw was…

< victori:#solr> anyway, are filter queries applied independently on the full dataset or one after another on a shrinking resultset?

As with many things in life, the answer is "It Depends"

In particular, the answer to this question largely depends on:

• If either/both of the queryResultCache / filterCache are enabled for collection (they are in the default configs)
• If the individual "Query" objects (q & zero or more fq parms) have caching enabled (it is by default)

… but further nuances come into play depending on:

• The effective cost param specified on each fq (defaults to '0' for most queries)
• The type of the underlying Query object created for each fq: Do any implement the PostFilter API?

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