Data loss

Undo for SQL Server.

Data loss

Postby kirkr » Mon Aug 14, 2006 2:50 pm

SQL Log Rescue Version:
DB Recovery Model: Simple
Auto Shrink: On
Issue: a record has been inserted into the table and at a later time deleted. SQL Log Rescue has this transaction however the script does not recover all the data;

* Some date fields that are actually NULL have been returned by SQL Log Rescue as '19000101 00:00:00.000'.
* Some bit fields that are actually zero (0) have been returned as NULL.
* Some nvarchar fields that are actually NULL have been returned as ''.
* Some nvarchar fields that are populated have been returned as ''.

I'm presuming this may be related to the recovery model and data loss but how did that 01/01/1900 date get involved and nulls returned as blanks, etc., could there be an issue with SQL Log Rescue?

Extract of some of the values from an SQL Log Rescue UNDO delete script;

...'19000101 00:00:00.000', NULL, NULL, NULL, NULL, N'13', N'625 (PAL) SD ', N'', NULL, NULL, NULL, '19000101 00:00:00.000', NULL, '19000101 00:00:00.000', NULL,...
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Joined: Mon Aug 14, 2006 2:18 pm

Postby Brian Donahue » Tue Aug 15, 2006 5:44 pm


Sorry but we don't have any explanation as to why Log Rescue is behaving like this. It would need to specifically cast the NULL data in the column to DateTime.MinVal, and there isn't any logic in the software doing that. We would probably need to see the dataabse to find the source of the problem.
Brian Donahue
Posts: 6590
Joined: Mon Aug 23, 2004 9:48 am

Postby kirkr » Tue Aug 15, 2006 5:56 pm

I've briefly reviewed since and it is SQL Server that interprets zero (0) as the date 01011900. I believe SQL Log Rescue has moved the data values from one column to the next, of a different data type, thus causing the issue. I'm not sure why as it correctly populated some records but not others. I am presuming SQL Log Rescue has interpreted the data values finding some form of character (or sequence of) in the transaction log and interpreted an additional data value.
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Joined: Mon Aug 14, 2006 2:18 pm

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