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Date: Tue, 2 Feb 2010 14:36:18 +0000 (UTC)
From: "Yonik Seeley (JIRA)" <jira@apache.org>
To: java-dev@lucene.apache.org
Subject: [jira] Commented: (LUCENE-2232) Use VShort to encode positions
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    [ https://issues.apache.org/jira/browse/LUCENE-2232?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12828633#action_12828633 ] 

Yonik Seeley commented on LUCENE-2232:
--------------------------------------

A branch mispredict can be more costly, depending on the context.
Cache misses are a major factor, and allowing speculative execution further ahead in the code (by correctly predicting branches) one can overlap those cache misses.
http://www.infoq.com/presentations/click-crash-course-modern-hardware

The complexity of modern hardware increases the need to do performance tests in context (unless it's clearly a win of course).

> Use VShort to encode positions
> ------------------------------
>
>                 Key: LUCENE-2232
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2232
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>            Reporter: Paul Elschot
>            Priority: Minor
>         Attachments: LUCENE-2232-nonbackwards.patch, LUCENE-2232-nonbackwards.patch
>
>
> Improve decoding speed for typical case of two bytes for a delta position at the cost of increasing the size of the proximity file.

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