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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: about isStored method
Date Sat, 26 Jan 2013 06:16:36 GMT
Because you can search on it? The stored fields are only those that should be displayed to
the user with search results. Imagine e.g. Google: Google displays in its search results the
title of the document and some "description", but it does not display the whole document text.
So in their case, they would "store" the title and some description of every document. On
the other hand you can search on the whole document, so the whole document text, which could
be megabytes of text data (like books), is "indexed".  Other cases where you have indexed-only
field that are not stored are:
- phonetic fields: Often, some fields are indexed a second time as a duplicate, but with a
phonetic filter assigned (that converts all tokens to phonetic representations). You can then
do a phonetic serach in addition to the exact matching search, but it makes absolutely no
sense to "store" the field 2 times.
- fields only used for faceting or sorting
- ...and many more

"stored fields" are for display to the user, "indexed fields" are for retrieval. They have
nothing to do with each other.

Uwe

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


> -----Original Message-----
> From: Lin Ma [mailto:linlma@gmail.com]
> Sent: Saturday, January 26, 2013 6:01 AM
> To: java-user@lucene.apache.org; ian.lea@gmail.com
> Subject: Re: about isStored method
> 
> Thanks Ian,
> 
> If the value is not stored in index, it cannot be retrieved on search results?
> My confusion is, if a field will not be in search result (isStored == false), why
> we need such field in Document?
> 
> regards,
> Lin
> 
> On Sat, Jan 26, 2013 at 4:37 AM, Ian Lea <ian.lea@gmail.com> wrote:
> 
> > If you're new to lucene why are you using such an old version?  Stored
> > means the value is stored in the index and can be retrieved later e.g.
> > for displaying on a search results page. Not stored means it isn't and
> > can't be.
> >
> > There was a similar question not long ago on this list - check the
> > archives.
> >
> > And read Lucene In Action.
> >
> >
> > --
> > Ian.
> >
> >
> > On Fri, Jan 25, 2013 at 4:58 PM, Lin Ma <linlma@gmail.com> wrote:
> > > Hi guys,
> > >
> > > I am new to Lucene and for isStored method for interface Fieldable (
> > >
> >
> http://lucene.apache.org/core/old_versioned_docs/versions/3_0_3/api/co
> > re/index.html
> > ),
> > > what are the logical meanings for stored and not stored? It is
> > > appreciate if anyone could show me an example. I searched many
> > > tutorials but not
> > found
> > > description for what means stored and what means not stored.
> > >
> > > thanks in advance,
> > > Lin
> >
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> >


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