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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3130) Reduce memory footprint of StoredRecordHeader
Date Mon, 31 Mar 2008 09:16:26 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3130?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-3130:
--------------------------------------

    Attachment: d3130-1a.diff

I have cleaned up the srh.diff patch and attached it as d3130-1a.diff. Derbyall ran cleanly,
and suites.All had 3 known failures (caused by DERBY-3519 and DERBY-3561). Although implementing
alternative 2b would save even more space, it seems like it's a much bigger rewrite, so I
don't think it's worth doing it at this point.

> 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: 10.4.0.0
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>            Priority: Minor
>         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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