[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

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 10.6.1.0
• Fix Version/s: 10.3.3.1, 10.4.2.1, 10.5.3.2, 10.6.1.0
• Component/s: SQL
• Bug behavior facts: Performance
• Assignee: Mamta A. Satoor
• Reporter: Mamta A. Satoor
• Created: 05/Feb/10 06:32
• Updated: 17/Jun/13 09:19
• Resolved: 02/Mar/10 00:28

Description

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.

Issue Links

• relates to: DERBY-1482 Update triggers on tables with blob columns stream blobs into memory even when the blobs are not referenced/accessed.