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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: Wild Card Query Performance
Date Fri, 29 Mar 2013 09:55:52 GMT
Hi,

It depends on the type of wildcard query. If you only have a prefix (ab*), they rewrite to
a simple PrefixQuery and this one is implemented exactly like in 3.x, so you only see the
speed improvements of Lucene 4.0 in the term dictionary and and other index components, not
related to the query itsself.

If you have wildcards like ab?xy, then this query will be multiple times faster than in 3.x,
because the "?" wildcard can only expand to a limited set of terms, while in Lucene 3.x, it
still scans all terms with prefix "ab". The same applies to other wildcard constructs, if
they limit more than just prefix.

Uwe

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de


> -----Original Message-----
> From: Arun Kumar K [mailto:arunk786@gmail.com]
> Sent: Friday, March 29, 2013 10:38 AM
> To: java-user
> Subject: Wild Card Query Performance
> 
> Hi Guys,
> 
> I have been testing the search time improvement in Lucene 4.0 from Lucene
> 3.0.2 version for Wildcard Queries (with atleast say 2 chars Eg.ar*).
> 
> For a 2GB size index with 4000000 docs, the following observations were
> made:
> 
> Around 3X improvement with and without STRING sort on a sortable field.
> 
> I guess this improvement is because of the Automation Query by Robert
> which is used in WildCard Queries.
> 
> As per mike's blog, FuzzyQueries are 100X times faster in 4.0 but these
> wildcard queries are not that faster comparatively.
> 
> I have used default codecs and postings format.
> 
> Did i miss something or is it the max improvement that we can expect
> currently for WildCard Queries?
> 
> 
> Arun


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