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Date: Wed, 12 Sep 2007 09:53:55 -0400
From: "Erick Erickson" <erickerickson@gmail.com>
To: java-user@lucene.apache.org
Subject: Re: regarding FieldSelector
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Well, it depends on what "improve the search process" means
in your context <G>..

But I had a case similar to yours that I wrote up in the Wiki where
my search times improved about 10X by using lazy loading. You
might want to read that entry here...

http://wiki.apache.org/lucene-java/FieldSelectorPerformance

Note the peculiar characteristics of my data set, I really suspect
that a 10x improvement in retrieval speed is atypical...

As for when lazily-loaded fields actually get loaded, I didn't really
have to explore it very fully, but a short experiment should do it
for you.....

Best
Erick

On 9/12/07, Mohammad Norouzi <mnrz57@gmail.com> wrote:
>
> Hi Grant,
> Really thanks for your nice document about advanced Lucene. it was very
> useful for me.
>
> as I understand, we can set some large fields to be lazily loading, now my
> question is when it will be loaded? it make sense when we call
> doc.get("field_name")
> it will load from the index, Am I right?
>
> in my application, I've provided a result set structure to navigate
> between
> results and documents and provide a get(String fieldname) method just like
> java.sql.ResultSet.getString() method, and also this result set implements
> HitCollector in order to collect my own ID rather than Lucene's document
> id,
> so I think I can set my field ID to be loaded always and the other fields
> to
> be lazily loading, Does this improve the search process?
>
> again, thank you very much indeed.
>
>
> On 9/12/07, Grant Ingersoll <gsingers@apache.org> wrote:
> >
> > Hi Mohammad,
> >
> > The typical use cases are:
> > 1. You have several small fields used in a results display and one or
> > two large fields (i.e. the original document) and you don't want to
> > pay the cost of loading the large fields for results display because
> > most of them won't be chosen.  When a result is chosen, the lazily
> > loaded field will be retrieved.
> >
> > 2. You only want to load certain fields, or the first field, or you
> > just want to know the size of a field.
> >
> > Basically, it gives you control over how fields are loaded from disk
> > in Lucene.
> >
> > See my ApacheCon Europe presentation http://cnlp.org/presentations/
> > slides/AdvancedLuceneEU.pdf for a few slides (towards the end) on
> > FieldSelector.
> >
> > On Sep 12, 2007, at 5:13 AM, Mohammad Norouzi wrote:
> >
> > > Hi all,
> > >
> > > Can anyone explain what is the FieldSelector and the usage or
> > > benefits of
> > > this structure? I read the javadocs but I can't get for what goal
> > > it is
> > > provided in Lucene.
> > >
> > > Thanks in advance
> > >
> > > --
> > > Regards,
> > > Mohammad
> > > --------------------------
> > > see my blog: http://brainable.blogspot.com/
> > > another in Persian: http://fekre-motefavet.blogspot.com/
> >
> > --------------------------
> > Grant Ingersoll
> > http://lucene.grantingersoll.com
> >
> > Lucene Helpful Hints:
> > http://wiki.apache.org/lucene-java/BasicsOfPerformance
> > http://wiki.apache.org/lucene-java/LuceneFAQ
> >
> >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> > For additional commands, e-mail: java-user-help@lucene.apache.org
> >
> >
>
>
> --
> Regards,
> Mohammad
> --------------------------
> see my blog: http://brainable.blogspot.com/
> another in Persian: http://fekre-motefavet.blogspot.com/
>

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