On Jan 13, 2006, at 21:42 , Leandro Guimarães Faria Corcete DUTRA wrote:
If you still declare the natural key(s) as UNIQUEs, you have just made
performance worse. Now there are two keys to be checked on UPDATEs
and
INSERTs, two indexes to be updated, and probably a SEQUENCE too.
For UPDATEs and INSERTs, the "proper" primary key also needs to be
checked, but keys are used for more than just checking uniqueness:
they're also often used in JOINs. Joining against a single integer
I'd think it quite a different proposition (I'd think faster in terms
of performance) than joining against, say, a text column or a
composite key.
Michael Glaesemann
grzm myrealbox com
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
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