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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Created: (DERBY-3112) AllocPages have wrong minimumRecordSize
Date Mon, 08 Oct 2007 07:58:51 GMT
AllocPages have wrong minimumRecordSize
---------------------------------------

                 Key: DERBY-3112
                 URL: https://issues.apache.org/jira/browse/DERBY-3112
             Project: Derby
          Issue Type: Bug
          Components: Store
    Affects Versions: 10.4.0.0
            Reporter: Knut Anders Hatlen
            Priority: Minor


AllocPage.createPage() contains this code at its beginning:

		super.createPage(newIdentity, args);

		// args[0] is the format id
		// args[1] is whether to sync the page to disk or not
		// args[2] is the pagesize (used by StoredPage)
		// args[3] is the spareSize (used by StoredPage)
		// args[4] is the number of bytes to reserve for container header
		// args[5] is the minimumRecordSize
		// NOTE: the arg list here must match the one in FileContainer
		int pageSize = args[2];
		int minimumRecordSize = args[5];
		borrowedSpace = args[4];

The variable minimumRecordSize is local and unused, so setting it has no effect. The local
variable hides a field with the same name inherited from StoredPage. That field is initialized
to args[4] when super.createPage() is called. According to the comment in AllocPage, args[4]
is the number of bytes to reserve for the container header (aka borrowedSpace), not the minimum
record size. (args[4] is however the minimum record size if the page is a plain StoredPage,
that's why super.createPage() will use that value.) I therefore believe that this code intended
to update StoredPage.minimumRecordSize, not a local, unused variable.

I don't know if this can lead to incorrect behaviour, but it doesn't look right.

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