Problem with execution of an update rule - Mailing list pgsql-general
From | Ken Winter |
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Subject | Problem with execution of an update rule |
Date | |
Msg-id | 3B7C35927527474784AAA4C300DA2FEE@KenIBM Whole thread Raw |
Responses |
Re: Problem with execution of an update rule
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List | pgsql-general |
I'm trying to implement a history-keeping scheme using PostgreSQL views and update rules. My problem is that one of the commands in one of my crucial update rules apparently never executes. Briefly, the history-keeping scheme involves: * Two tables: an "h table" that contains the columns for which we want to preserve a full history of all updates, and an "i table" that contains columns whose history we don't want to preserve. * A view of the two tables, showing all the columns of the h and I tables. * A set of rules that makes the view behave like a fully updatable table, while invisibly preserving a copy of the record as it existed prior to each update. The problem rule (see example in the "PS" below) is the one that fires when the user issues a SQL UPDATE against the view. This rule fires if the UPDATE has changed any column value. It is supposed to execute three commands: 1. Insert a new record into the _h table, containing the old values of the record being updated. This is the record that preserves the prior state of the record. 2. Update the existing h table record with the new values. 3. Update the existing i table record with the new values. The problem is that command 1 apparently never executes. That is, in response to an UPDATE against the view, a new h table record is NOT inserted - even though data changes in both the h and the i table are successfully recorded, and no error messages occur. I have tried changing the order of the 3 commands in the rule - no effect. Can you tell me what's wrong with this picture? ~ TIA ~ Ken PS: This example involves a view named "people", an h table named "people_h" (including columns "first_name" and "last_name"), an i table named "people_i" (including column "birth_date"), a sequence-assigned identifier "people_id" in both tables, some "effective" and "expiration" timestamps in "people_h", and some rules including this troublesome one: CREATE OR REPLACE RULE on_update_2_preserve AS ON UPDATE TO people WHERE ( (OLD.people_id <> NEW.people_id OR (OLD.people_id IS NULL AND NEW.people_id IS NOT NULL) OR (OLD.people_id IS NOT NULL AND NEW.people_id IS NULL )) OR (OLD.effective_date_and_time <> NEW.effective_date_and_time OR (OLD.effective_date_and_time IS NULL AND NEW.effective_date_and_time IS NOT NULL) OR (OLD.effective_date_and_time IS NOT NULL AND NEW.effective_date_and_time IS NULL )) OR (OLD.first_name <> NEW.first_name OR (OLD.first_name IS NULL AND NEW.first_name IS NOT NULL) OR (OLD.first_name IS NOT NULL AND NEW.first_name IS NULL )) OR (OLD.last_name <> NEW.last_name OR (OLD.last_name IS NULL AND NEW.last_name IS NOT NULL) OR (OLD.last_name IS NOT NULL AND NEW.last_name IS NULL )) OR (OLD._action <> NEW._action OR (OLD._action IS NULL AND NEW._action IS NOT NULL) OR (OLD._action IS NOT NULL AND NEW._action IS NULL )) OR (OLD.birth_date <> NEW.birth_date OR (OLD.birth_date IS NULL AND NEW.birth_date IS NOT NULL) OR (OLD.birth_date IS NOT NULL AND NEW.birth_date IS NULL ))) ) DO ( /* Copy the old values to a new record. Expire it either now (if no effective date was provided) or whenever the update query specifies.*/ INSERT INTO people_h ( people_id, first_name, last_name, effective_date_and_time, expiration_date_and_time) VALUES ( OLD.people_id, OLD.first_name, OLD.last_name, OLD.effective_date_and_time, NEW.effective_date_and_time) ; /* Update the current H record and make it effective as of either now (if no effective date was provided) or whenever the update query specifies.*/ UPDATE people_h SET people_id = NEW.people_id, first_name = NEW.first_name, last_name = NEW.last_name, _action = 'preserved', effective_date_and_time = CASE WHEN NEW.effective_date_and_time = OLD.effective_date_and_time THEN CURRENT_TIMESTAMP ELSE NEW.effective_date_and_time END WHERE people_id = OLD.people_id AND effective_date_and_time = OLD.effective_date_and_time ; /* Update I table. */ UPDATE people_i SET people_id = NEW.people_id, birth_date = NEW.birth_date, WHERE people_id = OLD.people_id; SELECT public.debug('Rule on_update_2_preserve fired','','',''); ) ; _____ I am using the Free version of SPAMfighter <http://www.spamfighter.com/len> . We are a community of 6 million users fighting spam. SPAMfighter has removed 392 of my spam emails to date. The Professional version does not have this message.
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