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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DERBY-5294) Triggers created prior to 10.9 release will continue to read all the columns from trigger table even after database has been upgraded to 10.9 and higher
Date Thu, 23 Jun 2011 22:00:48 GMT
Triggers created prior to 10.9 release will continue to read all the columns from trigger table
even after database has been upgraded to 10.9 and higher
--------------------------------------------------------------------------------------------------------------------------------------------------------

                 Key: DERBY-5294
                 URL: https://issues.apache.org/jira/browse/DERBY-5294
             Project: Derby
          Issue Type: Task
          Components: SQL
    Affects Versions: 10.7.1.1
            Reporter: Mamta A. Satoor


With DERBY-1482 (which went in 10.9 codeline), triggers will read only the columns needed
by the triggering sql and firing triggers. But this applies only to triggers created in 10.9
and higher. Any triggers created prior to 10.9 will not be able to take advantage of DERBY-1482
because those triggers do not keep the information about the trigger action columns. Currently,
the users will have to drop and recreate the triggers which use the REFERENCING CLAUSE and
were created prior to 10.9 to take advantage of DERBY-1482.

The alternative to manual drop and recreate of such triggers can be explored as part of this
jira. Couple options are
1)UPDATE sql should detect that the trigger does not have information about the trigger action
columns and hence it should make the trigger collect that information.
2)At the time of upgrade, when we mark all the SPSes invalid, detect the triggers which do
not have the information about the trigger action columns and make those triggers collect
that information.
3)Enhance ALTER TABLE COMPRESS to detect the triggers which do not have the information about
the trigger action columns and make those triggers collect that information. With this option,
users will still have to manually do ALTER TABLE COMPRESS to fix the triggers but atleast
they won't have to get the original trigger definitions and drop and recreate the triggers
using those original trigger definitions.

10.9 currently does not have central place where the trigger will go and collect the information
about trigger action columns. We do have code in ALTER TABLE DROP COLUMN to collect the trigger
action column info but it will probably better to have such a code in TriggerDescriptor so
it can be used by the approach taken to fix this jira.

Note that without the fix for this jira, the triggers created prior to 10.9 will work just
fine after upgrade to 10.9 and higher but they will not be able to prevent reading of columns
that are not necessary for the triggering sql and firing triggers

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