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From "Mirko Sertic" <mirko.ser...@web.de>
Subject Aw: Re: Re: Strange performance of Lucene 4.4.0
Date Mon, 09 Sep 2013 09:21:38 GMT
Hi

Basically i am running a load test. For every run i executed about 1 million queries on the
same index with the same query string, so it should be warmed up very well ;-) It performs
about 8x faster with an empty Sort() instance than the first option. Still do not get it.
An empty Sort instance should sort by score, according to the default constructor.
 
Providing no sort instance finally invokes

protected TopDocs search(Weight weight, ScoreDoc after, int nDocs) throws IOException

while providing a Sort instance finally invokes

protected TopFieldDocs search(Weight weight, FieldDoc after, int nDocs,
                                Sort sort, boolean fillFields,
                                boolean doDocScores, boolean doMaxScore) throws IOException
 
with doDocScores and doMaxScore set to false.

Seems like providing an empty Sort() instances should sort by score according to its default
constructor. But no scoring is done by the IndexSearcher, so there is nothing so sort at all.
So from this point of view the scoring computation does cause the slower queries.

Regards
Mirko

Gesendet: Montag, 09. September 2013 um 09:55 Uhr
Von: "Toke Eskildsen" <te@statsbiblioteket.dk>
An: "java-user@lucene.apache.org" <java-user@lucene.apache.org>
Betreff: Re: Aw: Re: Strange performance of Lucene 4.4.0
On Sun, 2013-09-08 at 15:15 +0200, Mirko Sertic wrote:
> I have to check, but my usecase does not require sorting or even
> scoring at all. I still do not get what the difference is...

Please describe how you perform your measurements. How do you ensure
that the index is warmed equally for the two cases?

- Toke


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