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Cascade Order

From: "Marty Alchin" <gulopine(at)hotmail(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Cascade Order
Date: 2004-07-28 13:34:31
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-general
Fir of all, hello to all of you. I'm new to this list, and I apologize if 
this has already been asked, but the mailing list archives don't seem to be 
responding at the moment for me to search through.

In my uses of PostgreSQL, I'm developing a revision control system for some 
of my data, and I'd like it to be handled in PostgreSQL to make the 
interface in the application much simpler. The challenge I face now is to 
create a rollback system so that when a revision is deleted, the data in the 
actual information table is rolled back to its state prior to the revision 
that was just deleted. I set up foreign keys in the revision table so it 
would cause a chain reaction and delete all revisions on that same document 
after the one to be deleted, but this is where it stops functioning as I 
need it to.

PostgreSQL deletes the requested row first, then cascades to the next row, 
which triggers a cascade to the next, and so on. For my rollback, however, I 
need to be able to delete the last revision first, and rollback one revision 
at a time until the initially specified revision is deleted.

Is there a way to instruct PostgreSQL to perform the cascade in reverse 
order like this, or do I need to create a seperate function to search for 
and delete the revisions without the aid of the foreign key? Any help in 
this area would be greatly appreciated.

Thank you,
Marty Alchin

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