Hi Andrzej, sorry for the late reply.
I have looked at the code. As far as I understand, you sort the posting lists based on the first doc skip. The first posting list will be the one who have the first biggest document skip. Do the sparseness of posting lists is a good predictor for sampling and ordering posting lists ? Do you know evaluation of such technique ?
In order to implement sorting based on frequency, we need the document frequency of each term. This information should be propagated through the Scorer classes (from TermScorer to higher level class such as ConjunctiveScorer). This will require a call to IndexReader.docFreq(term) for each of the term queries. Is docFreq call mean another IO access ?
Thanks for the clarification, Regards. -- Renaud Delbru Andrzej Bialecki wrote:
Renaud Delbru wrote: > Hi all, > > I am wondering if Lucene implements the query optimisation that consists > of ordering the posting lists based on the term frequency before > intersection ? > If yes, could somebody point me to the java class / method that > implements such strategy ? Lucene trunk: ConjunctionScorer, lines 85-103 - pay attention to the comments there, it's not strictly a sort by frequency, rather by the sampled "sparseness". -- Best regards, Andrzej Bialecki <>< ___. ___ ___ ___ _ _ __________________________________ [__ || __|__/|__||\/| Information Retrieval, Semantic Web ___|||__|| \| || | Embedded Unix, System Integration http://www.sigram.com Contact: info at sigram dot com --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
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