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help / color / mirror / Atom feedFrom: Mark Metson <gpurdy@fox.nstn.ns.ca>
To: Paul M. Aoki <aoki@postgres.Berkeley.EDU>
Cc: Michael Ubell <michael@montage.com>
Cc: postgres@postgres.Berkeley.EDU
Subject: Re: locking [was: Use by a Business]
Date: Tue, 31 May 1994 02:55:02 +0100
Message-ID: <Pine.3.89.9405310211.B1720-0100000@acamn.aca.uucp> (raw)
In-Reply-To: <199405310253.TAA20627@faerie.CS.Berkeley.EDU>
On Mon, 30 May 1994, Paul M. Aoki wrote:
> Michael Ubell <michael@montage.com> writes:
...
> (not that the last two messages have had anything to do with what
> the guy was asking..)
...
Ah but they do, they do. Locking is the crux of the problem. I have a
complete application running at a Collection Agency in Business Basic
under SCO Unix System V. Standard code developed across a number of
employers in which when you edit a masterfile record the record is locked
using an 'EXTRACT' until unlocked using a READ or WRITE. Meanwhile it
sits on user's screen over lunch or until per-input timeouts realise
they've gone to lunch. There are two pricetags, $2500 and $2300, one for
new unix, one for new BASIC (can never recall which is which), total
$4800, which come up every time they think about computerising another
branch office. Assuming they have $4800 on hand, we'd all feel better if
they spent it on something more constructive, like buying hardware or
paying me. I wanted GNU instead of UNIX in the first place, but it wasnt
available back then. Now, the free unix I kept telling them was on the
horizon is here, we want to move to it. We also would like to move from
the BASIC if it'd be cheaper to rewrite than to buy a copy per possible
new site, and may HAVE to move from BASIC if we cannot get Business Basic
for Linux. I have just this day discovered some ALPHA code for running
SCO SysV executables under Linux, so possibly I might be able to stay
with BASIC, but if not, postgres is the only thing I've seen that might
be useable in its place, other than to take some standard ISAM code and
write a shared-memory record-locks-table or somesuch for it; and since
Linux kernel support for arbitrary locks has no
deadlock-detection/protection in it, I am rather wary of potential
deadlock situations if I try to add a key with one task while deleting a
key with another task in the same index; I suspect record-level locks on
the blocks ofa Btree would be in real deadlock danger in such scenarios.
I guess Business Basic spoiled me, I had never spent much thought on what
nifty tricks the language was taking care of for me in its
innocent-seeming record handling system.
Blessed Be. -MarkM-
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To: postgres@postgres.berkeley.edu
Cc: gpurdy@fox.nstn.ns.ca, aoki@postgres.Berkeley.EDU, michael@montage.com
Subject: Re: locking [was: Use by a Business]
In-Reply-To: <Pine.3.89.9405310211.B1720-0100000@acamn.aca.uucp>
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