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From "Fuad Efendi" <>
Subject RE: SOLR vs SQL
Date Wed, 02 Sep 2009 16:40:48 GMT
> This article explains in-depth why calculating facets is not practical in
> pure SQL:
-> "The problem is that SQL isn't really capable of expressing set

But this article is not applicable to described use case: we are
_faceting_on_filtered_query_results_only_, and filters are defined by facets
(same as).

- no need to count docset intersections in this specific use case. Just
execute 20 SQL queries with filters (if you have 20 'foreign keys' for an
entity). Performance is like [log(n)] where n is index size... with SOLR, it
is linear, it is not log(n)...

Same with SOLR vs. Lucene, standard Lucene queries "filter1:value1 AND
facet2:value2" ... "filter1:value1 AND facet2:value99" are functionally the
same as SOLR faceting (99 docset intersections in RAM) and (sooner or later)
implementation and performance will be similar very close (Lucene vs.

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