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From Maxim Patramanskij <...@osua.de>
Subject Re[2]: Does order of BooleanQuery clauses affect search performance?
Date Mon, 05 Dec 2005 06:33:17 GMT
Hello Paul,

Friday, August 26, 2005, 8:40:44 PM, you wrote:

PE> On Friday 26 August 2005 17:58, Paul.Illingworth@saaconsultants.com wrote:
>> 
>> A simple question and I guess it may have been asked before.
>> 
>> Does the order of Querys in a BooleanQuery affect search speed? By this I
>> mean if the first clause of a BooleanQuery only returns a few results and
>> the second clause returns lots of results and the two are ANDed is this
>> faster than the other way around? Similarly, does searching stop if no

PE> Subqueries of BooleanQuery are called clauses in Lucene.
PE> The order of clauses does not matter.
PE> Having only required clauses does matter, normally a lot.

>> results are found and the logical operations would mean no results can be
>> found (similar to Javas "short circuiting" of logical operations)?

PE> The development version tries to do as much "short circuiting" as possible.
PE> Lucene 1.4.3 neither short circuits for "or" (optional clauses)
PE> nor for "not" (prohibited clauses).
PE> Both do short circuiting for "and" (required clauses).

PE> Regards,
PE> Paul Elschot


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-- 
Best regards,
 Maxim                            mailto:max@osua.de


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