Very Computer

by **Rajes** » Mon, 14 Jul 2003 11:22:26

Can some one explain the Pros and Cons of using Identity columns?

-Rp?

by **Rob Verschoo** » Tue, 15 Jul 2003 01:41:25

Quote:> Can some one explain the Pros and Cons of using Identity columns?

> -Rp?

Pro: they're a very fast way of generating sequential numbers (since
no disk I/O or transactional locking is needed for generating a new
value.

Cons: in pre-12.0: there's a risk of "identity gaps", see
www.sypron.nl/idgaps.html for details.
In 12.0+: identity gaps can be limited or avoided with the
'identity_gap' setting -- when you use this, there are few
disadvantages left (but those are solved in 12.5.0.3 and 12.5.1).

HTH,

Rob
-------------------------------------------------------------
Rob Verschoor

Certified Sybase Professional DBA for ASE 12.5/12.0/11.5/11.0
and Replication Server 12.5

New book(coming soon): 'Tips, Tricks & Recipes for Sybase ASE'
For details, see http://www.sypron.nl/ttr

http://www.sypron.nl
Sypron B.V., P.O.Box 10695, 2501HR Den Haag, The Netherlands
-------------------------------------------------------------

by **osy4** » Tue, 15 Jul 2003 02:30:02

see http://www.sypron.nl/idgaps.html

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by **Anthony Mandi** » Tue, 15 Jul 2003 21:09:43

> In 12.0+: identity gaps can be limited or avoided with the
> 'identity_gap' setting -- when you use this, there are few
> disadvantages left (but those are solved in 12.5.0.3 and 12.5.1).

What disadvantages have been solved in 12.5.x?

-am ? 2003

by **Rob Verschoo** » Wed, 16 Jul 2003 03:12:06

> > In 12.0+: identity gaps can be limited or avoided with the
> > 'identity_gap' setting -- when you use this, there are few
> > disadvantages left (but those are solved in 12.5.0.3 and 12.5.1).

> What disadvantages have been solved in 12.5.x?

> -am ? 2003

In 12.5.0.3, some identty-related built-ins were added as well as the
command 'set identity_update'.
In the beta version of 12.5.1, it is possible to reset the identity
counter to an arbitrary value with sp_chgattribute.

Rob
-------------------------------------------------------------
Rob Verschoor

Certified Sybase Professional DBA for ASE 12.5/12.0/11.5/11.0
and Replication Server 12.5

New book(coming soon): 'Tips, Tricks & Recipes for Sybase ASE'
For details, see http://www.sypron.nl/ttr

http://www.sypron.nl
Sypron B.V., P.O.Box 10695, 2501HR Den Haag, The Netherlands
-------------------------------------------------------------

by **Anthony Mandi** » Wed, 16 Jul 2003 13:24:55

> In 12.5.0.3, some identty-related built-ins were added as well as the
> command 'set identity_update'.
> In the beta version of 12.5.1, it is possible to reset the identity
> counter to an arbitrary value with sp_chgattribute.

Very interesting ...

-am ? 2003

Very Computer

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