Posted by uli2003wien on 09/14/05 13:30

Dear group,

we are running a SQL-Server Database which is about 30 GB large. The
purpose of this database is to contain periodic data from automatic
devices which insert values into some tables.

Unfortunately most of these tables don't have a key (and a key can only
be introduced when the application programmers have changed their
software). Tables have this structure

deviceno timestamp data

where we expect for every device and timestamp one row of data.

In the ongoing operation it happens that the index of this large table
gets corrupted and a select from this table yields 2 rows for some
devices.

In fact a select "SELECT DEVICENO, TIMESTAMP, COUNT(*) FROM TABLE GROUP
BY DEVICENO, TIMESTAMP HAVING COUNT(*) > 1" returns lots of data.

After rebuild of the indexes the table is "clean" again.

What could cause the index corruption ?

Missing key?
Faulty application program ?
a combination of both ?

How can i prevent this from happening again, as long as there is no
updated database / application ?

I'd be grateful for any useful comment

Regards

Uli

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