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Posted by Erland Sommarskog on 07/02/07 21:37
Roy Harvey (roy_harvey@snet.net) writes:
> Pure speculation.....
>
> From your description the process occurs in two steps. The first
> selects the data from T1, the second loads it to T2. That sounds like
> there is an intermediate data store. If the purge of that store
> occurs after the load to T2, and the load to T2 failed, then the file
> or table or whatever was not empty when the next extract from T1
> occurred. If the extract from T1 appends the data it would have been
> appending data that was already there from the failed run.
>
> If the two tables must remain synchronized the extract and load should
> execute within a single transaction.
And to add this: you must also make sure that if any errors occurs during
the transaction, that the transaction is rolled back. For many errors,
execution continues, so if you have error-checking, part of the transaction
will still be committed.
Without seeing the code, speculations is all you can get.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
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