Category : Paradox DBMS
Archive   : TECH91.ZIP
Filename : TI597.ASC

PRODUCT : Paradox NUMBER : 597
VERSION : All
OS : DOS
DATE : September 11, 1991 PAGE : 1/3

TITLE : Causes of Table Damage and Use of Tutility




There are several things that can cause table damage. This is
not due to any problems with Paradox, but is an unfortunate part
of operating in the DOS environment with minimal error checking
and write redundancy. The best we can do is to be aware of the
causes and do our best to avoid them. Below are a list of things
that can cause a table to become damaged. These are arranged
roughly by how frequently the type of error occurs.

Operator Error - Turning off or rebooting the computer while
Paradox is on the screen. Just because there are no images on
the screen does not mean it is OK to shut the system down, as
parts of the table may remain only in RAM. ALWAYS exit Paradox
to DOS before rebooting or powering down. This also means that
it is not OK to shut down the machine while shelled out to DOS
from Paradox using the Tools/More/ToDos, ALT-O, or CTRL-O
command. Possible indicators:

o Stray PARADOX.LCK files in a networked environment can
indicate someone exiting Paradox improperly. Make certain
no-one is logged in to Paradox and delete any *.LCK files.
Rebuild any tables being used when Paradox was exited.


o Stray PARADOX.RUN files indicate that someone has rebooted
the machine after shelling out to Paradox using the ToDos
or CTRL-O or ALT-O commands. Be certain no one is in
Paradox OR shelled out from Paradox and delete any
remaining PARADOX.RUN files.


TSR Programs - Programs that run in the "background" are
sometimes "ill-mannered" about the way they return control to the
main program. If the program does not restore the bus and RAM
back to the original state, this can cause damage. Even popping

up a TSR; using its hotkey, at a bad time (in the middle of a
sort for instance) can cause problems. Possible indicator:

o Paradox will often freeze constantly, or reports memory
conflicts.


Hard or Floppy Disk Errors - Any time a disk is not operating up
to specifications, one of the first signs is corrupted tables.













PRODUCT : Paradox NUMBER : 597
VERSION : All
OS : DOS
DATE : September 11, 1991 PAGE : 2/3

TITLE : Causes of Table Damage and Use of Tutility




Any failure to read or write to the media properly can damage a
table. A bad controller card can also cause problems. You
should test your disk frequently for errors using some utility
software such as PC-Tools or Norton Utilities or any similar
products. Possible indicator:

o Run CHKDSK /F to check for bad sectors, cross-linked files
which were written to the disk incorrectly. This will
move the lost sectors to *.CHK files. Check your DOS
manual for further details.


A.C. Voltage Variations - Black outs, brown outs, line "spikes",
line "dips". Example: The HP Laserjet II places power dips on
line and can damage Paradox tables. A computer with a power
supply that is too weak for all the boards or devices connected
to it can generate a voltage that is too low. The best way to
avoid these problems is a quality surge protector or even a UPS
(Uninterrupted Power Supply) which can give you time to shut down
Paradox. Possible indicator:

o In a networked environment, PARADOX.LCK files can show up
from this situation also. Check for any *.LCK files.
This might indicate that one or more workstations went
down due to a power surge (or user error).


RAM Problems - Parity errors in memory chips, CPU speed set
higher than the memory can refresh (appears to be a problem in
some high speed clones), an extended memory board in the machine
that has NOT been INITIALIZED (via the software provided by the
board manufacturer). These are all hardware problems which can
cause table damage. Possible indicators:

o Parity interrupt errors, tables constantly going bad
without fitting any other symptoms, etc.


Unexpected Condition Errors - Any situation in which Paradox
exits unexpectedly can cause table damage. A typical error
message begins with Unexpected Condition. If this happens, you
should rebuild the table. A damaged table or family member
(forms, reports, etc.) can also cause these Unexpected













PRODUCT : Paradox NUMBER : 597
VERSION : All
OS : DOS
DATE : September 11, 1991 PAGE : 3/3

TITLE : Causes of Table Damage and Use of Tutility




Conditions, so be aware of other sources for the original damage
as well.

Network Problems - A malfunctioning server, with any of the above
problems, bad cable connector, bad I/O RAM, bad packet
transmission (interference), malfunctioning network board, or
even a net line that is too long, or just getting old can all be
responsible for damaging tables.

If table damage occurs, you should exit Paradox as soon as you
notice it. The signs of table damage can be varied, from data
apparently disappearing to actually throwing you out Paradox.
Anytime something that normally works goes wrong, you should
first check all your tables for damage.

From your DOS command line, change directories to your Paradox
directory using the following command: cd \pdox35. If you named
your directory something other than pdox35, you will need to
enter the appropriate directory name.

Type tutility to enter the TUTILITY program. You will see a menu
at the top of the screen. Select the Directory option to change
directories to where your data is kept. Then select the Rebuild
option and enter your table name to rebuild that table. You can
also select to the Verify option to test the table for damage,
but some types of damage elude the verify command, so if there is
any doubt, select Rebuild. After rebuilding all your tables, you
can then exit TUTILITY and re-enter Paradox.

If this does not work, you can also attempt to repair your
damaged tables by exporting the table to an ASCII delimited text
file, and creating a new table by importing the data into another
table name. Note: DO NOT append the data to the existing table,
although you can append it to a new table with an identical
structure. The best alternative is to keep backups of your data.

NOTE: If you have an earlier version of Paradox, you will need
to install TUTILITY yourself. This program consists of two
files, TUTILITY.EXE and TUTILITY.DOC. You can find these files
on your Installation/Sample Tables Diskette (the one with your
Serial Number on it), or failing that, examine your Personal
Programmer Disk #6 in the UTIL subdirectory.