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From "Delalande, Thierry" <Thierry.Delala...@uk.daiwacm.com>
Subject Short circuit AND or subquerying in lucene for performance
Date Wed, 15 Feb 2012 11:33:42 GMT
Hi,

 

I've been looking for a short circuit AND operator in Lucene or a way to
do subquerying.

Basically for queries such as field1:foo AND field2:*bar, I think it
would be highly beneficial to restrict evaluation of the second field on
the result of the first to avoid scanning the index in its entirety due
to the leading wildcard.

This can be seen as a subquery (running a query only on the result of a
first query) or as a short circuit AND, and would exist for performance
reasons.

Using SAND to denote the short-circuit variety, the short-circuit
expression x SAND y is equivalent to the conditional expression if x
then y else false.

 

So my example query would be more performant expressed as field1:foo
SAND field2:*bar

Other examples:

field1:(foo AND *bar) would be more performant expressed as field1:(foo
SAND *bar)

 

Please let me know what's already possible in terms of subquerying and
what it would take to implement this new operator in Lucene.

 

Thanks


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