Andy Lester created SOLR-15859:
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Summary: Add handler to dump filter cache
Key: SOLR-15859
URL: https://issues.apache.org/jira/browse/SOLR-15859
Project: Solr
Issue Type: Improvement
Security Level: Public (Default Security Level. Issues are Public)
Reporter: Andy Lester
It would be very helpful to be able to inspect the contents of the filterCache.
I'd like to be able to query something like
{{/admin/caches?type=filter&nentries=1000&sort=numHits+DESC}}
nentries would be allowed to be -1 to get everything.
It would be nice to see these data items for each entry. I don't know which are
available, but I'm thinking blue sky here:
* cache key, exactly as stored
* Timestamp when the entry was inserted
* Whether the insertion of the entry evicted another entry, and if so which one
* Timestamp of when this entry was last hit
* Number of hits on this entry forever
* Number of hits on this entry over some time period
* Number of documents matched by the filter
* Number of bytes of memory used by the filter
These are the sorts of questions I'd like to be able answer:
* "I just did a query that I expect will have added a cache entry. Did it?"
* "Are my queries hitting existing cache entries?"
* "How big should I set my filterCache size? Should I limit it by number of
entries or RAM usage?"
* "Which of my FQs are getting used the most? These are the ones I want in my
firstSearcher queries." (I currently determine this by processing my old solr
logs)
* "Which filters give me the most bang for the buck in terms of RAM usage?"
* "I have filter X and filter Y, but would it be beneficial if I made a filter
X AND Y?"
* "Which FQs are used more at certain times of the day? (Assuming I take
regular snapshots throughout the day)"
I imagine a response might look like:
{{{}}
{{ "responseHeader": {}}
{{ "status": 0,}}
{{ "QTime": 961}}
{{ },}}
{{ "response": {}}
{{ "numFound": 12104,}}
{{ "filterCacheKeys": {}}
{{ [}}
{{ "language:eng": {}}
{{ "inserted": "2021-12-04T07:34:16Z",}}
{{ "lastHit": "2021-12-04T18:17:43Z",}}
{{ "numHits": 15065,}}
{{ "numHitsInPastHour": 2319,}}
{{ "evictedKey": "agelevel:4 shippable:Y",}}
{{ "numRecordsMatchedByFilter": 24328753,}}
{{ "bytesUsed": 3041094}}
{{ }}}
{{ ],}}
{{ [}}
{{ "is_set:N": {}}
{{ ...}}
{{ }}}
{{ ],}}
{{ [}}
{{ "language:spa": {}}
{{ ...}}
{{ }}}
{{ ]}}
{{ }}}
{{}}}
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