RE: Difference: Concatenated PK - artificial PK

From: Martin Kendall <Martin.Kendall_at_Rubus.com>
Date: Wed, 17 Jan 2001 11:48:21 -0000
Message-Id: <10744.126872@fatcity.com>

Hi Helmut,

I think that perhaps you have answered your own question really.

I have always found that PK's made up of just a Sequence are much more usable than concatenated keys. One can then create a Unique Key if required to control the Table Content.

-----Original Message-----
From: Helmut Daiminger [mailto:hdaiminger_at_vivonet.com] Sent: 16 January 2001 18:43
To: Multiple recipients of list ORACLE-L Subject: Difference: Concatenated PK - artificial PK

Hi!

I have a question concerning artifical keys and concatenated primary keys.

Usually it is recommended using concatenated primary keys and not introduce an artifical PKs (e.g. through a sequence). The problem with that is that we will have PKs made up of three or four columns and when nesting into deeper hierarchies PKs will get very long.

What is the performance impact of having a concatenated PK? I would have to do three joins instead of one...

Would it be a good idea to introduce an artificial key (e.g. sequence) and use the concatenated key as an alternate (unique) key and put an index on it?

This is 8.1.6 on Win2k.

Thanks,
Helmut

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Please see the official ORACLE-L FAQ: http://www.orafaq.com
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Author: Helmut Daiminger
  INET: hdaiminger_at_vivonet.com

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