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From roz dev <rozde...@gmail.com>
Subject Re: Size of lucene norm file
Date Sun, 18 Sep 2011 08:17:48 GMT
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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