Steve Peacocke asked:
> I'm interested in you opinions/facts regarding an issue I was
> recently made
> aware of. I am currently writing a LAN based program (client server is NOT
> AN OPTION) and have, by default started using Paradox files.
> I realise some data corruption in the fault of not using dbiSaveChanges in
> the AfterPost event.
No matter what LAN database you use there is the *certainty* that you will
get data corruption if some of your clients are running Windows 95 with
older version of the VREDIR.VXD, or running against a WinNT server with
incorrectly configured optimistic locking. Microsoft strikes again with a
whole slew of nasty bugs that have been causing us problems for the last
three years.
Other bigger players than us have also found the problems, check out
http://www.faircom.com/product_tech/ctree/redirect.htm for a good discussion
of the problems, or for more technical information regarding the network
redirector issue from Microsoft Support, read on the following:
Possible Network File Damage with Redirector Caching
(MS Support Article ID: Q148367)
Locking Error or Computer Hangs Accessing Network Database Files
(MS Support Article ID: Q142803)
Possible Database File Damage When Data Is Appended
(MS Support Article ID: Q174371)
Possible Network Data Corruption If Locking Not Used
(MS Support Article ID: Q152186).
The unknown issue is if the BDE engines for Paradox or DBF format files have
appropriate checking to ensure that these bugs do not bite too hard. In our
data engine we have had to add in extra paranoid checks to ensure that we
can detect these bugs if they occur, and with the new Windows software also
add in versioning checks on VREDIR.VXD to ensure that people are warned
about the potential problems.
Cheers, Max.
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