RE: Best way to make a table of non-unique rows, unique?

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-
bounces@xxxxxxxxxxxx] On Behalf Of Dave Odom
Sent: Thursday, May 29, 2008 5:27 PM
To: midrange-l@xxxxxxxxxxxx
Subject: RE: Best way to make a table of non-unique rows, unique?


My thinking was to put triggers on the vendor's tables I need. These
triggers would be looking for INSERTs, UPDATEs or DELETEs. When those
were detected, I would copy the row to a similar table with all the same
columns but with the addition of the columns you mention and/or a
datetimestamp column and an "operation" column where I would insert an
"I", "U" or "D" for the operation that caused the insert in the "similar"
table. Then I could put a unique index on the columns you mentioned
and/or my datetimestamp and operation column which would make each row
unique. I realize this would, in essence, create rows of "history" but
I think this is a faster solution than complex programming and if the
users know about the data when they create their queries they can take
that into account and either disregard whatever rows they don't need or
take advantage of the history if that better suits them.

Honestly, this makes no sense to me. Instead of propagating the original file, you're going to
propagate a history file???

How would that be useful? Unless the users are solely interested in the history, they'd kill
themselves trying to find the "current" information out of the history file that corresponds to the
current data in the original file. Plus, are you going to seed it with entries for all records so
that they can find a record if the data doesn't get changed anytime soon?

You could try using triggers or the journaled entries for the file to make a "shadow copy" of the file
by basically using RRN as the unique key for the file. But there's pitfalls with that; the reuse of
deleted records or a RGZPFM on the original will cause you problems among other things....

There's a very good reason datapropagator wants a unique key....

Charles



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