TRIGGERS referencing system temporal tables
Since we are in DB2 V10 we use triggers with bi-temporal tables
(system temporal + business temporal table) to implement complex
relational integrity rules that can not be defined using standard
primary/foreign keys. It's related to simple INSERT or
DELETE/UPDATE with FOR PORTION OF BUSINESS_TIME statement.
All of our development was based on recommendation made in
IBM DeveloperWorks document "Managing time in DB2 with temporal
consistency Enforce time-based referential integrity" from July 12, 2012
written by Mr. Matthias Nicola and Mr. Martin Sommerlandt.
In DB2 V10 and DB2 V11 conversion mode, there was no problem.
It was possible to define a trigger referencing a SYSTEM TEMPORAL or
BI-TEMPORAL table in the WHEN clause. Since we are in DB2 V11, we
receive an SQLCODE=-270 each time that the package trigger is rebound.
In DB2 V11, there is a procedure to circumvent this issue,
we have to alter the BI-TEMPORAL table to DROP the VERSIONING,
DROP/CREATE the trigger, add the VERSIONING and finaly REBIND
the TRIGGER PACKAGE with bind option SYSTIMESENSITIVE NO.
Even if this procedure is less obvious than before, it works.
According to IBM, in DB2 V12, this solution will not work anymore and
we will have to review/drop the triggers that are impacted and implement
the RI in the programs that are updating the tables.
This solution will work too but the RI will not be verified if the
update is done via spufi, datastudio, ...
With triggers it was also verified in such cases.
This solution is than a lot less secured, and more difficult to
maintain (one TRIGGER per type of modification vs multiple programs