View Incident Report

Minor

Reported By: Chris Thornton
Reported On: 11/19/2013
For: Version 4.37 Build 3

# 3994 Table Optimization Exposes Checksum Errors in Records from Past Bug in DBISAM

We’ve got a periodic optimization job currently running on a few dozen of our largest clients, and it has uncovered some sort of corruption in a table. The table appears fine until the optimize runs, but if you re-verify, it shows Checksum errors on records.

I followed these steps, and had the corresponding results:

Verify Table: OK
Optimize Table: OK
Verify Table: Checksum errors on records #167 and #448.
Repair Table: Fixed errors mentioned above.
Verify Table: OK
Optimize Table: OK
Verify Table: OK
Optimize Table: OK

It will be OK from now on, after repair has been run at least once.

Comments

This problem would appear in tables created by very early versions of DBISAM 4.x that didn't zero-out string fields completely when they were assigned values. Table optimization would cause these fields to be zeroed out completely, thus making the checksum for the record invalid. The table optimization now re-sets the checksum for each record, so if there are any such checksum issues, they will be fixed during the table optimization.

Resolution

Fixed Problem on 11/23/2013 in version 4.38 build 1

Products Affected

DBISAM Additional Software and Utilities
DBISAM ODBC Client-Server
DBISAM ODBC Client-Server with Source
DBISAM ODBC Standard
DBISAM ODBC Standard with Source
DBISAM ODBC Trial
DBISAM VCL Client-Server
DBISAM VCL Client-Server with Source
DBISAM VCL Standard
DBISAM VCL Standard with Source
DBISAM VCL Trial

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