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From: steve@violet.berkeley.edu (Steve Goldfield)
Newsgroups: comp.databases
Subject: Re: dBASE IV Problems
Message-ID: <1989Aug31.153729.20204@agate.uucp>
Date: 31 Aug 89 15:37:29 GMT
References: <205@cerc.wvu.wvnet.edu.edu> <3520009@hpindda.HP.COM> <135@cica.cica.indiana.edu>
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Organization: University of California, Berkeley
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In article <135@cica.cica.indiana.edu> mr@cica.cica.indiana.edu (Michael Regoli) writes:
#>keithb@hpindda.HP.COM (Keith Broussard) writes:
#>
#>>1.  Indexes seem to get corrupted so that large chunks of data are
#>>often skipped during sequential searches, or cyclical repetitions of
#>>records occur.  I.E.  An alphabetical listing will skip all names
#>>between R and V, for example, or a list will get to Z and start again
#>>at C, over and over and over...
#>
#>i've been experiencing this as well.  i'm *damn* glad that i'm
#>not alone in this.  
#>
#>ask mr. zuckerman in my database of over 2,500 names.  when indexed
#>on the lastname field, mr. zuckerman (and mr. zehr, mr. zobrist, et
#>al.) mysteriously disappear on a random basis.
#>
#>we've created mr. zzzzbar to hold the file's bottom from dropping out
#>but sometimes he goes away as well.
#>
#>it's a pain that i've had to include a reindex menu option (!cringe!)
#>on our secretary's dbms.  
#>
#>what gives?!  alastair (awd@dbase.UUCP)?  has this been reported to a-t?
#>
#>--
#>michael regoli
#>mr@cica.indiana.edu 
#>regoli@iubacs.bitnet
#>...rutgers!iuvax!cica!mr

I've seen similar behavior in all versions of dBASE, including
McMax, I've used. Generally, these problems are caused by
abnormal exits from the program through hard or soft crashes.
In most cases, packing and reindexing clears them up. Packing
is necessary before reindexing because such crashes often
create non-Ascii characters in the database which interfere
with its operation. You may also have to delete or clean up
such records. I haven't used dBASE IV, but I doubt that it
is immune to the same kind of problem.

In general, once I get the bugs out of a program, I find
that most of the problems users have are caused by bad
data, either entered by them or created by a crash.
I usually check the data first (after packing and reindexing
before trying to solve problems). Even in Ingres, I recently
found that a retrieval problem was caused by unexpected
data values.

Steve Goldfield