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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3934) Improve performance of reading modified Clobs
Date Mon, 09 Feb 2009 10:46:59 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3934?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kristian Waagan updated DERBY-3934:
-----------------------------------

    Attachment: derby-3934-6a-UTF8Reader_remove_method.diff

Patch 6a removes the now unused method 'readUnsignedShort'. It is no longer used because the
reading of the header bytes have been moved outside the reader class.

Committed to trunk with revision 742380.

> Improve performance of reading modified Clobs
> ---------------------------------------------
>
>                 Key: DERBY-3934
>                 URL: https://issues.apache.org/jira/browse/DERBY-3934
>             Project: Derby
>          Issue Type: Improvement
>          Components: JDBC
>    Affects Versions: 10.5.0.0
>            Reporter: Kristian Waagan
>            Assignee: Kristian Waagan
>             Fix For: 10.5.0.0
>
>         Attachments: derby-3934-1a-clob_replace_test.diff, derby-3934-2a-intclob_new_methods.diff,
derby-3934-3a-clobupdreader_utf8reader.diff, derby-3934-3a-clobupdreader_utf8reader.stat,
derby-3934-4a-getinternalreader_cachedlength.diff, derby-3934-5a-UTF8Reader_cleanup.diff,
derby-3934-6a-UTF8Reader_remove_method.diff
>
>
> The performance of reading modified Clobs is poor, which is demonstrated by running a
test program selecting a 10 MB Clob and then getting the contents using getSubString:
>  - unmodified Clob (StoreStreamClob) : ~1 300 ms
>  - modified Clob (TemporaryClob): ~156 000 ms
> In this case, the Clob was modified by changing the first character.
> A number of subtasks will be created to handle the various issues, which will be related
to both performance and code cleanup.
> For a brief overview, see http://www.nabble.com/Suggestion-for-improving-ClobUpdatableReader-and-related-code-to20308303.html

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