Just Learned - SCOPE_IDENTITY() sometimes returns incorrect value

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SCOPE_IDENTITY() sometimes returns incorrect value

Mar 6 2012 12:00AM by Guenter

When using INSERTs on large tables (> 1 millon rows), the SCOPE_IDENTITY() or @@identity functions sometimes return wrong results.

(This was NOT supposed to be fixed in SQL Server versions older than 2012!)

Update: It seems the problem has been fixed in SQL2008 R2 SP1 CU5 (see http://support.microsoft.com/kb/2019779). I have not checked it yet, as in my company CU's are not widely used (because of internal complexity caused by it). Thanks to Johan Bijnens pointing that out.

5 Comments

This really worries me! Why do you think 'sometimes' it works and 'sometimes' it doesn't.

Do you insert just ONE row immediately followed by set @i=@@identity?

How do you access the database when this happens? Can you reproduce it in Management Studio. Or is it happening via something like JDBC or .NET?

commented on Mar 6 2012 3:29AM

dishdy

17 · 10% · 3262

Apparently Cumulative Update 5 for SQL Server 2008 R2 SP1 has a fix for this bug ... It's been known for ages @@identity should be avoided and scope_identity() is more stable.

ref: http://sqlblog.com/blogs/aaron_bertrand/archive/2012/02/23/two-new-cumulative-updates-for-sql-server-2008-r2-are-available.aspx

Worth the test.

commented on Mar 6 2012 5:01AM

Johan Bijnens

1493 · 0% · 13

Here are two causes of incorrect scope_identity() values as reported at Microsoft Connect. As far as I can tell, If you avoid these you should be okay:

If a MERGE command has a MATCHED condition and there is a row NOT MATCHED SCOPE_IDENTITY() becomes equal to @@IDENTITY
SCOPE_IDENTITY() sometimes returns incorrect value when a plan uses parallelism--WITH (MAXDOP 1) will help.

@Johan - it's not an issue of @@identity vs. scope_identity(). Both can give the wrong value.

commented on Mar 6 2012 11:23AM

ErikEckhardt

65 · 3% · 887

I have used ident_current function and it did not gave wrong value any time.

commented on Mar 9 2012 11:47PM

kr.roopesh

817 · 0% · 35

Till now i dont get any issues with ident_current, possibly i need got more experience...grt guys...

commented on Mar 13 2012 4:03PM

Robert Dennyson

11 · 14% · 4419

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"SCOPE_IDENTITY() sometimes returns incorrect value" rated 5 out of 5 by 13 readers