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From "Yonik Seeley (JIRA)" <>
Subject [jira] Resolved: (LUCENE-448) optional norms
Date Sat, 29 Oct 2005 04:16:55 GMT
     [ ]
Yonik Seeley resolved LUCENE-448:

    Fix Version: CVS Nightly - Specify date in submission
     Resolution: Fixed
      Assign To: Yonik Seeley

> optional norms
> --------------
>          Key: LUCENE-448
>          URL:
>      Project: Lucene - Java
>         Type: New Feature
>   Components: Index
>     Versions: CVS Nightly - Specify date in submission
>     Reporter: Yonik Seeley
>     Assignee: Yonik Seeley
>      Fix For: CVS Nightly - Specify date in submission
>  Attachments: omitNorms.txt
> For applications with many indexed fields, the norms cause memory problems both during
indexing and querying.
> This patch makes norms optional on a per-field basis, in the same way that term vectors
are optional per-field.
> Overview of changes:
>  - Field.omitNorms that defaults to false
>  - backward compatible lucene file format change: FieldInfos.FieldBits has a bit for
>  - IndexReader.hasNorms() method
>  - During merging, if any segment includes norms, then norms are included.
>  - methods to get norms return the equivalent 1.0f array for backward compatibility
> The patch was designed for backward compatibility:
>  - all current unit tests pass w/o any modifications required
>  - compatible with old indexes since the default is omitNorms=false
>  - compatible with older/custom subclasses of IndexReader since a default hasNorms()
is provided
>  - compatible with older/custom users of IndexReader such as Weight/Scorer/explain since
a norm array is produced on demand, even if norms were not stored
> If this patch is accepted (or if the direction is acceptable), performance for scoring
 could be improved by assuming 1.0f when hasNorms(field)==false.

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