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Date: Wed, 9 Sep 2009 15:39:57 -0700 (PDT)
From: "Mike Matrigali (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Updated: (DERBY-3130) Reduce memory footprint of
 StoredRecordHeader
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     [ https://issues.apache.org/jira/browse/DERBY-3130?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mike Matrigali updated DERBY-3130:
----------------------------------

    Fix Version/s: 10.3.3.0

commited 813145:

backporting fix (revision 643875) from trunk to 10.3 branch.

> Reduce memory footprint of StoredRecordHeader
> ---------------------------------------------
>
>                 Key: DERBY-3130
>                 URL: https://issues.apache.org/jira/browse/DERBY-3130
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store
>    Affects Versions: 10.4.1.3
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>            Priority: Minor
>             Fix For: 10.3.3.0, 10.4.1.3, 10.5.1.1
>
>         Attachments: d3130-1a.diff, SmallRecordsTest.java, srh.diff
>
>
> Derby's page cache often has a memory footprint that is much larger than pageSize*pageCacheSize. One large contributor to the footprint is the array of StoredPageHeader objects in BasePage. The memory consumed by these objects can be as large as, and sometimes even larger than, the byte arrays containing the raw page data. (See for instance http://www.nabble.com/How-much-derby-need-memory--tf3307655.html.) Reducing the size of the StoredPageHeader objects could therefore reduce Derby's memory footprint significantly, especially if the page cache is large and contains many pages from tables with small records or from indices.

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