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https://issues.apache.org/jira/browse/DERBY-3934?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kristian Waagan updated DERBY-3934:
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Attachment: derby-3934-2a-intclob_new_methods.diff
'derby-3934-2a-intclob_new_methods.diff' adds two new methods to the
InternalClob interface; getUpdateCount and isReleased.
They can be used to determine if the content of a Clob has been changed, and if
the internal Clob representation has been changed or the Clob has been closed.
The isReleased() method will be used to detect when a read-only Clob
representation is changed to a writable representation due to a user's request
to modify the content (i.e. setString).
The code is currently not being used, but it will be by the new implementation
of ClobUpdatableReader (not yet posted - I do have a prototype if anyone is
interested).
Patch ready for review.
> 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
> Attachments: derby-3934-1a-clob_replace_test.diff,
> derby-3934-2a-intclob_new_methods.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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