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From "Mohamed Nufail (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5207) Fix the description of Derby's stored page format, found on the web site.
Date Sun, 01 Apr 2012 12:32:29 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5207?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mohamed Nufail updated DERBY-5207:
----------------------------------

    Attachment: DERBY-5207.patch

Attached a patch containing the suggested modifications.
                
> Fix the description of Derby's stored page format, found on the web site.
> -------------------------------------------------------------------------
>
>                 Key: DERBY-5207
>                 URL: https://issues.apache.org/jira/browse/DERBY-5207
>             Project: Derby
>          Issue Type: Improvement
>          Components: Web Site
>    Affects Versions: 10.9.0.0
>            Reporter: Rick Hillegas
>         Attachments: DERBY-5207.patch
>
>
> I have found some discrepancies between Derby code and the description of the stored
page format found on our web site (http://db.apache.org/derby/papers/pageformats.html):
> 1) The website correctly says that the page header is 56 bytes long. However, you get
58 bytes if you add up the values in the left column of http://db.apache.org/derby/papers/pageformats.html#storedpage.
The extra 2 bytes come from the inclusion of an unsigned short representing "% of the page
to keep free for updates". That field does not appear in StoredPage.readPageHeader(). The
field should be removed from the web site page.
> 2) That table has an additional problem: the "spare for future use (encryption uses to
write random bytes here)" field is correctly listed as being 4 bytes long (in the left column)
but the middle column says that it is a long. That middle column should say that the value
is an integer.
> 3) Although the first 4 bytes of the AllocPage header are devoted to a Formatable ID,
the actual Formatable ID only occupies the leading 2 bytes of the page. The next 2 bytes are
unused. The first line of the "Format of Alloc Page" table should note this fact.
> 4) There is no RECORD_INITIAL bit in the record header status field.

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