Ok, my "naive" thinking about FieldCache: for each Term we can quickly retrieve DocSet. What are memory requirements? Theoretically, [maxdoc]x[4-bytes DocumentID], plus some (small) array to store terms pointing to (large) arrays of DocumentIDs.
Mike suggested http://issues.apache.org/jira/browse/LUCENE-1990 to make this memory requirement even lower... but please correct me if I am wrong with formula, and I am unsure how it is currently implemented... Thanks, Fuad > -----Original Message----- > From: Fuad Efendi [mailto:f...@efendi.ca] > Sent: November-02-09 8:21 PM > To: solr-user@lucene.apache.org > Subject: RE: Lucene FieldCache memory requirements > > Mark, > > I don't understand this: > > so with a ton of docs and a few uniques, you get a temp boost in the RAM > > reqs until it sizes it down. > > Sizes down??? Why is it called Cache indeed? And how SOLR uses it if it is > not cache? > > > And this: > > A pointer for each doc. > > Why can't we use (int) DocumentID? For me, it is natural; 64-bit pointer to > an object in RAM is not natural (in Lucene world)... > > > So, is it [maxdoc]x[4-bytes], or [maxdoc]x[8-bytes]?... > -Fuad > > > >
