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Posted to java-user@lucene.apache.org by Kevin Burton <bu...@rojo.com> on 2005/05/31 09:06:50 UTC
Finding minimum and maximum value of a field?
I have an index with a date field. I want to quickly find the minimum
and maximum values in the index.
Is there a quick way to do this? I looked at using TermInfos and
finding the first one but how to I find the last?
I also tried the new sort API and the performance was horrible :-/
Any ideas?
Kevin
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Re: Finding minimum and maximum value of a field?
Posted by John Wang <jo...@gmail.com>.
You can try to load the fieldcache:
if you get the StringIndex from the fieldcache, the last element in
the lookup array is the largest value (lexically) in the field.
-John
On 6/7/05, sergiu gordea <gs...@ifit.uni-klu.ac.at> wrote:
>
>
> Kevin Burton wrote:
>
> > I have an index with a date field. I want to quickly find the minimum
> > and maximum values in the index.
> >
> > Is there a quick way to do this? I looked at using TermInfos and
> > finding the first one but how to I find the last?
> >
> > I also tried the new sort API and the performance was horrible :-/
> >
> > Any ideas?
>
> You may keep a history of the MIN and MAX values in an external file.
> Let's say, you can write in a text file the MIN_DATE and MAX_DATE,
> and keep them up to date when indexing, deleting documents.
>
> Best,
>
> Sergiu
>
> >
> > Kevin
> >
>
>
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Re: Finding minimum and maximum value of a field?
Posted by sergiu gordea <gs...@ifit.uni-klu.ac.at>.
Kevin Burton wrote:
> I have an index with a date field. I want to quickly find the minimum
> and maximum values in the index.
>
> Is there a quick way to do this? I looked at using TermInfos and
> finding the first one but how to I find the last?
>
> I also tried the new sort API and the performance was horrible :-/
>
> Any ideas?
You may keep a history of the MIN and MAX values in an external file.
Let's say, you can write in a text file the MIN_DATE and MAX_DATE,
and keep them up to date when indexing, deleting documents.
Best,
Sergiu
>
> Kevin
>
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Re: Finding minimum and maximum value of a field?
Posted by Tony Schwartz <to...@simpleobjects.com>.
Only way I see to do this is to get a TermEnum for that field, and grab the first. Then
iterate until you find the last one. This is similar behavior to the TermEnum.skipTo
method. A better solution would be to record the minimum and maximum dates in the index
as you index them. Each time you insert a new date, update the min/max if needed. This
data would reside outside the index of course.
Tony Schwartz
tony@simpleobjects.com
"What we need is more cowbell."
> I have an index with a date field. I want to quickly find the minimum
> and maximum values in the index.
>
> Is there a quick way to do this? I looked at using TermInfos and
> finding the first one but how to I find the last?
>
> I also tried the new sort API and the performance was horrible :-/
>
> Any ideas?
>
> Kevin
>
> --
>
>
> Use Rojo (RSS/Atom aggregator)! - visit http://rojo.com.
> See irc.freenode.net #rojo if you want to chat.
>
> Rojo is Hiring! - http://www.rojonetworks.com/JobsAtRojo.html
>
> Kevin A. Burton, Location - San Francisco, CA
> AIM/YIM - sfburtonator, Web - http://peerfear.org/
> GPG fingerprint: 5FB2 F3E2 760E 70A8 6174 D393 E84D 8D04 99F1 4412
>
>
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> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-user-help@lucene.apache.org
>
>
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