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From Øystein Grøvlen (JIRA) <j...@apache.org>
Subject [jira] Commented: (DERBY-2586) BlobClob4BlobTest.tesPositionAgressive takes very long time
Date Wed, 23 May 2007 11:53:16 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12498209

Øystein Grøvlen commented on DERBY-2586:

> Once I changed the blob/clob to hold only 4k in memory and if it exceeds
> use a file it started taking very long because of the file i/o over
> heads. If we change the max buffer size (higher than 4k) we will be
> getting better performance for clob/blob of length smaller than the new
> value. But there may be risk of getting out of memory exception if we
> keep the value large and there are too many active blob and clob.I think
> we need not make the buffer size too large, as right now after making
> the stream buffered we are able to get performance comparable to the
> older implementation.

I think it is important that temporary storage is only used when the LOB is updated.  Hence,
when reading a LOB, one should make sure that the LOB is not written to temporary storage,
regardless of size.

> BlobClob4BlobTest.tesPositionAgressive takes very long time
> -----------------------------------------------------------
>                 Key: DERBY-2586
>                 URL: https://issues.apache.org/jira/browse/DERBY-2586
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC
>            Reporter: Øystein Grøvlen
>         Assigned To: Anurag Shekhar
>             Fix For:
>         Attachments: derby-2586.diff
> Dan reports that BlobClob4BlobTest.tesPositionAgressive takes very long to run:
> > In a test run (junit-all) of 5,816 fixtures that took 4124 seconds (~68mins) *three*
fixtures took 53% of the total time.
> >
> > testPositionAgressive                1564.684 seconds
> > testNetworkServerSecurityMechanism    497.280 seconds
> > testTypesInActionStatement            128.928 seconds 
> Knut Anders reports that this behavior is fairly new:
> > It seems like it started taking a lot more time at revision 530085. I had
> > run the tests at an earlier revision.
> This was a check-in for DERBY-2346.  Since Anurag is currently on vacation, I will try
to look into this.

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