Database Corruption - Can it be avoided?

Database Corruption - Can it be avoided?

Post by vgeh » Fri, 12 May 1995 04:00:00



We are running into problems with our Foxbase+ and Foxpro 2.6a for
DOS applications that run at about 1500 different locations.  From time
to time we will get calls where one or more databases are damaged.
Either the user will get error messages that the memo file is invalid
or missing (we have a utility that can corect that 99% of the time) or
they will get error messages that the dbf isn't a dbf (which we can
seldon repair) or the field type and length for one field is totally
wacked out.  There has got to be a cause for these inconsistent
problems.  I'm not aware of any commands in Foxpro that allow you to
mess around with the header of a dbf or fpt directly (excluding the low
level file i/o which we don't use.), so I don't know how to rewrite our
system to prevent the corruptions.  It appears to occur primarily in
network environements, although we have had it happen on single user
systems as well (but seldom - but perhaps that due to the fact that the
majority of our clients are running in a multi-user environment).  At
any rate, I've got to find a solution.  How can I prevent these
corruptions from occuring?

Thanks,
Rick

fax: U.S.A. 314.524.0670

 
 
 

Database Corruption - Can it be avoided?

Post by Keith Trangma » Tue, 16 May 1995 04:00:00


I used to get a lot of this, and it was 98% due to the users switching
off or rebooting the machine without first closing down the application.
I resolved it in part by giving them an earful down the phone, and also
putting a check for *.TMP files in the batch routine that starts the APP.
If it found any in the FP working directory, it displayed a warning about
not logging out properly then went off to rebuild all the index files for
ten minutes. If they've got to wait 10 minutes each time, they soon learn
to log off properly.

Not a programmatic solution, but it certainly worked for me!

Keith Trangmar, Harlend Computer Services
Dartford, Kent. UK.


 
 
 

Database Corruption - Can it be avoided?

Post by G.A.D.Mil » Thu, 18 May 1995 04:00:00



>We are running into problems with our Foxbase+ and Foxpro 2.6a for
>DOS applications that run at about 1500 different locations.  From time
>to time we will get calls where one or more databases are damaged.
>Either the user will get error messages that the memo file is invalid
>or missing (we have a utility that can corect that 99% of the time) or
>they will get error messages that the dbf isn't a dbf (which we can
>seldon repair) or the field type and length for one field is totally
>wacked out.

The message that the dbf isn't a dbf can be fixed easily enough. There
are several freeware programs that will do it. Check what's available
on http://www.state.sd.us/people/colink/fox_page.htm
There should be something there, or in one of the linked sites to help
you. Tell your users not to reboot while an application is running!

Drummond Miles

 
 
 

1. Tip: how to avoid database corruption

Very often there are messages 'My Access 2.0 database corrupts. What to do?
Help!'
I think I found a partial solution. It applies to applications which use a
lot of data throuput 24 hrs a day 7 days a week (like a background data
processing). The answer is: do not use SQL queries with dynasets and snapshots.
Limit yourself only to table/index manipulation and you will never get
a corrupted database. Of course, it requires a lot of coding, however, maybe
it is worth doing. It is like a return to those file based databases for
example Raima ot C-ISAM.

Regards

Cezar

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