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From "Earwin Burrfoot (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1604) Stop creating huge arrays to represent the absense of field norms
Date Tue, 14 Apr 2009 19:25:14 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12698886#action_12698886
] 

Earwin Burrfoot commented on LUCENE-1604:
-----------------------------------------

Yep, that was my blunder. :)

bq. An alternate approach that would eliminate this overhead is to subclass the scorers that
use norms and create an appropriate scorer that doesn't require the check. The drawback of
this approach would be that it is harder to maintain.
Somebody recently raised a topic on specialized Lucene, with classes generated from templates,
hardwiring various choices. Guys at MG4J generate a custom indexReader for each possible combination
of index settings. So the idea of separate scorers might be valid, if we're going optimization-freak
way. (and we don't have to support them separately) 

By the way, why everything surrounding norms map is heavily synchronized? I haven't found
a single write to the map outside of initialize().

> Stop creating huge arrays to represent the absense of field norms
> -----------------------------------------------------------------
>
>                 Key: LUCENE-1604
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1604
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>    Affects Versions: 2.9
>            Reporter: Shon Vella
>            Priority: Minor
>             Fix For: 2.9
>
>         Attachments: LUCENE-1604.patch
>
>
> Creating and keeping around huge arrays that hold a constant value is very inefficient
both from a heap usage standpoint and from a localility of reference standpoint. It would
be much more efficient to use null to represent a missing norms table.

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