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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3934) Improve performance of reading modified Clobs
Date Mon, 19 Jan 2009 13:35:59 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-3934-5a-UTF8Reader_cleanup.diff

Patch 5a removes a constructor and a method called only from that constructor.
Updated the code in EmbedCallableStatement20 to use the new constructor.

Running regression tests, will commit tomorrow if the tests pass.

> 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:
>            Reporter: Kristian Waagan
>            Assignee: Kristian Waagan
>             Fix For:
>         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
> 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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