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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3934) Improve performance of reading modified Clobs
Date Mon, 15 Dec 2008 11:41:44 GMT

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

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

    Fix Version/s: 10.5.0.0

Committed patch 4a to trunk with revision 726683.

Work remaining:
  o See if a byte/char position cache can be used [more efficiently] to improve repositioning
performance.
  o Cleaning up after the changes in UTF8Reader.

> 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
>
>
> 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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