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From "Anurag Shekhar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2586) BlobClob4BlobTest.tesPositionAgressive takes very long time
Date Mon, 21 May 2007 07:36:16 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12497371
] 

Anurag Shekhar commented on DERBY-2586:
---------------------------------------

sorry for the late response.
In Blob/clob before making the changes the data was held in memory 
depending on the free space in the page. So some times even huge 
clob/blob can be used as String. In case of testPositionAggressive all 
the tests were running in this mode and String.indexOf was giving result 
very fast.

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.




> 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: 10.3.0.0
>
>         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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