Solr/ElasticSearch - Document lookup by ID -> query or filterQuery?

Question

I just wonder what I am supposed to use for a lookup by ID.

This thread Solr Query on Unique Integer Field seems to use a query.

But it is not what is said here: Search document by id very slow

And here: http://lucene.472066.n3.nabble.com/Solr-Unique-Key-Field-Should-Apply-on-q-search-or-fq-search-td4003066.html But I'm not reusing the same query because the lookups can be on any ID

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ElasticSearch provides natively a lookup by id, someone knows what is happening under the hood of ElasticSearch lookup so that I can eventually use the same strategy with Solr?

Thanks

Answer 1

You should still use Filter Query cause you may search the same id some time later which would be much faster in performance in comparison to the q query

fq - Provide an optional filtering query.
Results of the query are restricted to searching only those results returned by the filter query. Filtered queries are cached by Solr . They are very useful for improving the speed of complex queries.