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Date: Thu, 25 Oct 2007 10:00:04 +0000 (GMT)
From: mark harwood <markharw00d@yahoo.co.uk>
Subject: Re: Lucene Queries Over User-Editable Dynamic Categories of Documents
To: java-user@lucene.apache.org
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Message-ID: <693739.47758.qm@web26015.mail.ukl.yahoo.com>

There are 2 considerations when caching filter results:=0A=0A1) What was th=
e criteria used to produce the results?=0A2) What version of the index were=
 these results taken from?=0A=0ACachingWrapperFilter takes care of 2) by us=
ing WeakHashMap keyed on IndexReader.=0A=0AThe filter you pass to CachingWr=
apperFilter must play it's part in taking care of 1) by implementing hashco=
de/equals.=0A=0AYou can then maintain an LRU hashmap of CachingWrapperFilte=
rs to keep only the most popular filters.=0A=0AIncidentally, contrib's XMLQ=
ueryParser handles all this for you with a simple "CachedFilter" tag:=0A=0A=
<FilteredQuery>=0A    <Query>=0A        <UserQuery>"Brittany Spears"</UserQ=
uery>=0A    </Query>    =0A    <Filter>=0A        <CachedFilter>=0A        =
    <RangeFilter fieldName=3D"date" lowerTerm=3D"19970409" upperTerm=3D"199=
70412"/>=0A        </CachedFilter>=0A    </Filter>    =0A</FilteredQuery>=
=0A=0A=0ACheers=0AMark=0A=0A----- Original Message ----=0AFrom: lucene user=
 <luz290@gmail.com>=0ATo: java-user@lucene.apache.org=0ASent: Thursday, 25 =
October, 2007 10:36:14 AM=0ASubject: Re: Lucene Queries Over User-Editable =
Dynamic Categories of Documents=0A=0AWhat do you means by 'Most caches are =
held in WeakHashMap...' is this=0Acaching provided by CachingWrappingFilter=
 or do we have to implement it=0Aourselves? I assume the former.=0A=0AWe wi=
ll share results of our testing as soon as we have any - not sure=0A how=0A=
generalizable they will be.=0A=0AYou have been super helpful! Very grateful=
! Thanks!=0A=0AOn 10/24/07, markharw00d <markharw00d@yahoo.co.uk> wrote:=0A=
>=0A> lucene user wrote:=0A> > Thanks for all your help!=0A> >=0A> > We are=
 using Lucene 2.1.0 and TermsFilter seems to be new in Lucene=0A> 2.2.0.=0A=
> > I have not been able to find SortedVIntList in the javadocs at all.=0A>=
 >=0A>=0A> No, SortedVIntList is in the patch I provided a link to earlier.=
=0A>=0A>=0A> > Because both SortedVIntList and a regular BitSet are based o=
n=0A Lucene=0A> > Document Numbers, which are not permanent, It seems we wi=
ll need to=0A> > generate these objects fresh at least once per session. An=
y=0A comments,=0A> > about that? Do I have that correct?=0A> >=0A> Yes. Mos=
t caches tend to be held in WeakHashMap keyed on IndexReader=0A so=0A> that=
 when a new reader takes over old caches are automatically=0A garbage=0A> c=
ollected.=0A>=0A>=0A> > Our application includes the following filter imple=
mentation that=0A we use=0A> for=0A> > a=0A> > slightly different end user =
category problem. We could easily use=0A it for=0A> our=0A> > current probl=
em as well.=0A> >=0A> > Is TermsFilter sufficiently better (faster, more co=
mpact, more=0A correct,=0A> > etc.) to make upgrading=0A> > very important?=
=0A> >=0A> TermsFilter is in "contrib" and is stand-alone so should work wi=
th=0A most=0A> Lucene versions.=0A> Your implementation looks to scan the w=
hole termEnum whereas=0A TermsFilter=0A> looks up only the selected terms u=
sing reader.termDocs(term).=0A> Benchmarking will tell you which is faster.=
 I'd be interested to know=0A> the results.=0A>=0A> Cheers=0A> Mark=0A>=0A>=
=0A> ---------------------------------------------------------------------=
=0A> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org=0A> Fo=
r additional commands, e-mail: java-user-help@lucene.apache.org=0A>=0A>=0A=
=0A=0A=0A=0A=0A      ______________________________________________________=
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