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From "Kim Haase (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5698) Document performance issue with 2-arg versions of setXXXStream methods for LOBs
Date Fri, 11 May 2012 13:28:57 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5698?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13273246#comment-13273246
] 

Kim Haase commented on DERBY-5698:
----------------------------------

Thanks, Kristian! So would it be better to turn the sentence into a note that says something
like the following?

"If you omit the length argument when the stream object is a LOB greater than a single page
in size, performance will be impaired if you later retrieve the length of the LOB. However,
if you are simply inserting or reading data, performance is unaffected. See the derby.storage.pageSize
property for information about setting the page size."

Further tweaks welcome ...
                
> Document performance issue with 2-arg versions of setXXXStream methods for LOBs
> -------------------------------------------------------------------------------
>
>                 Key: DERBY-5698
>                 URL: https://issues.apache.org/jira/browse/DERBY-5698
>             Project: Derby
>          Issue Type: Improvement
>          Components: Documentation
>    Affects Versions: 10.8.2.2
>            Reporter: Kim Haase
>            Assignee: Kim Haase
>         Attachments: DERBY-5698.diff, DERBY-5698.stat, DERBY-5698.zip
>
>
> The PreparedStatement.setAsciiStream and other methods have a 3-arg form that includes
the length of the stream and a 2-arg form that does not. If the 2-arg form is used, Derby
has to calculate the length every time the method is called. With LOBs, especially large ones,
this can cause a major performance impact, especially if the method is called repeatedly.
This should be documented where appropriate.
> Kristian, please feel free to correct or amplify anything I've said here.

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