Re: Separate PK in Jxn Tbl?
Date: Mon, 28 Jan 2008 17:02:03 -0000
Message-ID: <sYCdnaAh2NsWlwPanZ2dnUVZ8uCdnZ2d_at_pipex.net>
"David Cressey" <cressey73_at_verizon.net> wrote in message news:U6nnj.8$1f.5_at_trndny02...
>
> One problem with cascading updates occurs when you want to relate data
> still
> in the database to data that was extracted from the database at an earlier
> point in time. This includes, but is not limited to, data in the log
> file.
Good points, and I will always concede that these are the kinds of external factors that in practice force one into using more synthetic keys than we'd like. Happily in my case the problem isn't too bad because we have a very nice journal analyzer that quickly reveals any key updates.
I hope I have also been pretty careful to warn people that creating redundant copies of data outside the database will cause all the problems one always associates with redundant copies of data. We tend to do a lot of refreshes instead of hoping our snapshots haven't mutated too badly. (In a way it's been a chicken and egg solution: we never allowed the egg, so we don't have to deal with the chicken! :-) We also make use of replication in several systems, and to our replicator an updated key is just another update.
But to repeat, I do understand synthetic keys will sometimes be forced on me. I don't insist they can always be avoided. They are my just last resort, not my first.
Roy Received on Mon Jan 28 2008 - 18:02:03 CET