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Date: Wed, 2 Feb 2011 11:01:29 +0000 (UTC)
From: "Derek Hulley (JIRA)" <jira@apache.org>
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Subject: [jira] Commented: (DBCP-352) Repeated calls to getMetadata in a
 transaction leads to performance degredation
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    [ https://issues.apache.org/jira/browse/DBCP-352?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12989597#comment-12989597 ] 

Derek Hulley commented on DBCP-352:
-----------------------------------

Phil's suggested fix for DBCP-330 will also address this problem.

> Repeated calls to getMetadata in a transaction leads to performance degredation
> -------------------------------------------------------------------------------
>
>                 Key: DBCP-352
>                 URL: https://issues.apache.org/jira/browse/DBCP-352
>             Project: Commons Dbcp
>          Issue Type: Bug
>    Affects Versions: 1.2.2, 1.3.1, 1.4
>         Environment: PostgreSQL, MySQL, JDK 1.6
>            Reporter: Derek Hulley
>            Priority: Critical
>             Fix For: 1.3.1, 1.4.1
>
>         Attachments: DBCPMetadataTest.zip
>
>
> During long-running transactions that utilize conditional logic based on the database metadata, it is possible to get thousands of calls to Connection.getMetaData.  An ArrayList is built up containing objects which are never removed (this is the cause of DBCP-330).  However, the array is shared with all other PreparedStatements, so the array scan and modification time keeps rising as the transaction progresses.
> I will attempt to attach an Eclipse project; profiling (or even a few JStacks) will show that most of the time is spent scanning the cluttered and growing array for objects to remove.

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