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We never had (many) issues with corruption-- after we had fun with some 3rd party disks on the S/38, the disk vendor upgraded the disks so we could use CheckSum (?) (ie software RAID), and enough extra memory so we wouldn't feel any degradation-- we've been RAIDed ever since!

Paul E Musselman
PaulMmn@xxxxxxxxxxxxx

-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Alan Campin
Sent: Monday, August 28, 2017 4:50 PM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Subject: Re: Database design question

Yep, in the bad old days you never put a key on the physical because of
corruption but with today's hardware it just never happens or at least I
have not seen it in many, many moons.

On Mon, Aug 28, 2017 at 1:44 PM, Musselman, Paul <
pmusselman@xxxxxxxxxxxxxxxx> wrote:

Ours as well-- IIRC, in the early S/38 / AS/400 days the thought was that
since a Physical File consisted of the data portion and an index, you were
out of luck if the index got corrupted-- you'd lose your master file!

Of course, in most cases you could CPYF FROMRCD(1) to read by RRN instead
of by key, and salvage your data.

The problem was overblown; but some applications...


Paul E Musselman
PaulMmn@xxxxxxxxxxxxx


-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of
Rob Berendt
Sent: Monday, August 28, 2017 1:58 PM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Subject: RE: Database design question

*SNIP*

That being said however, our ERP package has no primary nor unique keys on
the underlying table. They have a key on some of the logicals but do not
specify unique. In theory you could have duplicate keys but their
programming logic doesn't permit it (from transactions done within the
programming logic).

I think the thing was 40 years ago there was certain corruption which was
easier to recover from if your table did not have any keys on it. Don't
laugh, I think that is really the reason.

*SNIP*
--


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