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From "Uwe Schindler" <...@thetaphi.de>
Subject RE: Size of lucene norm file
Date Sun, 18 Sep 2011 08:30:48 GMT
Hi,

You can disable norms for fields where you don't need them. For standard
full text searches, they are important, but for e.g. primary key lookups or
numeric fields or fields that are only used for sorting, they are useless.

Uwe

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


> -----Original Message-----
> From: roz dev [mailto:rozdev29@gmail.com]
> Sent: Sunday, September 18, 2011 10:18 AM
> To: java-user@lucene.apache.org
> Subject: Re: Size of lucene norm file
> 
> Norms (*.nrm)
> 
> Norms are an index time normalization factor that can be factored into
scoring.
> Document and field boosts as well as length normalization are applied with
> norms. When in memory, norms occupy one byte per document for each field
> with norms on, even if only one document has norms on for that field. The
> Norms file does some book keeping and stores the byte for each document.
If
> you modify norms, modifications will be tracked in a new norms
> file,* seg_prefix_X.sN ,*were N is the field number, and X is the norms
> generation.
> 
> http://www.lucidimagination.com/blog/2009/03/18/exploring-lucenes-
> indexing-code-part-2/
> 
> as per this link, norms seem to be costly one
> 
> 
> 
> 
> 
> 
> On Sat, Sep 17, 2011 at 11:59 PM, janwen <tom.grade1986@163.com> wrote:
> 
> >
> > What is NORM file?
> >
> >
> >
> >
> > On 2011-9-18 5:20, roz dev wrote:
> >
> >> Hi,
> >>
> >> I want to estimate the size of NORM file that lucene will generate
> >> for a
> >> 20
> >> Gb index which has 2.5 Million Docs and 50 fields in each document.
> >>
> >> Is there any formula to predict it?
> >>
> >> And, what is the RAM cost of this nrm file.
> >>
> >> Thanks
> >> Saroj
> >>
> >>
> >
> >
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