ALTER TABLE DROP COLUMN should make use of information in SYSTRIGGERS to detect
column used through REFERENCING clause to find trigger dependencies
---------------------------------------------------------------------------------------------------------------------------------------------------
Key: DERBY-4988
URL: https://issues.apache.org/jira/browse/DERBY-4988
Project: Derby
Issue Type: Bug
Components: SQL
Affects Versions: 10.7.1.1
Reporter: Mamta A. Satoor
At the time of ALTER TABLE DROP COLUMN, Derby checks if the column being
dropped in a trigger column and if so, then it will not drop the column if it
is being done in RESTRICT mode or it will drop the trigger while dropping the
column in CASCADE mode. This does not implement SQL standard to it's entirety.
**************************************
SQL standard says following about ALTER TABLE DROP COLUMN RESTRICT and trigger
dependency in CREATE TRIGGER section
If RESTRICT is specified, then C shall not be referenced in any of the
following
d) Either an explicit trigger column list or a triggered action column set of
any trigger descriptor.
(The triggered action column set included in the trigger descriptor is the set
of all distinct, fully qualified names of columns contained in the <triggered
action>.)
**************************************
What is missing from Derby implementation from SQL standard point of view is
detected triggered action column set.
Starting 10.7(with DERBY-1482), Derby started keeping track of trigger action
columns which are referenced through REFERENCING clause. This information can
be used to improve the behavior of ALTER TABLE DROP COLUMN in 10.7 and higher.
This will not cover all the trigger action columns since columns referenced
without the REFERENCING clause are not tracked anywhere at this point. More
work will need to be done to implement SQL standard completely. But we can take
a step forward by using the information available in 10.7 and higher to detect
trigger action columns which are referenced through REFERENCING clause
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
