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Date: Tue, 2 Mar 2010 00:28:05 +0000 (UTC)
From: "Mamta A. Satoor (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-4538) If the CREATE TRIGGER does not have
 the REFERENCING clause, then there is no need to keep before and after
 values for the triggering table
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    [ https://issues.apache.org/jira/browse/DERBY-4538?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12839933#action_12839933 ] 

Mamta A. Satoor commented on DERBY-4538:
----------------------------------------

Knut, thanks for reviwing the patch. I committed the chnages after removing the redundant ;

I will go ahead and close this issue. 

> If the CREATE TRIGGER does not have the REFERENCING clause, then there is no need to keep before and after values for the triggering table
> ------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-4538
>                 URL: https://issues.apache.org/jira/browse/DERBY-4538
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.6.0.0
>            Reporter: Mamta A. Satoor
>            Assignee: Mamta A. Satoor
>            Priority: Minor
>         Attachments: DERBY4538_NoReferencingClause_diff_v1.txt, DERBY4538_NoReferencingClause_diff_v2.txt, DERBY4538_NoReferencingClause_stat_v1.txt, DERBY4538_NoReferencingClause_stat_v2.txt
>
>
> In order for the trigger action to have access to before and after values of the triggering table, the CREATE TRIGGER should use the REFERENCING clause. Without the REFERENCING clause, old and new values of triggering table can't be accessed by the trigger action. Based on this, we can improve Derby memory utilization by not keeping old and new values if REFERENCING clause is missing. It will be good to see if the code already does this optimization and if not, then introducing this optimization will definitely be very useful when the triggering table could have LOB columns.

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