Jamie Collins wrote:
If my table had columns for surname, initials and telephone number and
my queries predominantly use BETWEEN on the surname column, having the
table physically ordered on telephone number may make my queries
perform worse than if the physical order was on surname (can you
imagine trying to use a paper copy telephone directory ordered on
telephone number g ?!)

As I said, the choice of PK should be determined by the SQL DML e.g.
you are interested in page locks for updates in a multi-user
environment, I'm interested in query performance, etc.

Oops! I meant to add:

In other words I want to fetch rows on the same page and contiguous
pages; you want to maximise the chances of the rows each user will be
interested in are on different pages (am I correct?) I think in my
simple contacts example physically ordering on surname would provide
good concurrency as well. Whatever, it's clear we are both thinking
about the Jet implementation (i.e. contiguous storage on disk) when
considering PKs. Can everyone else say the same?

Jamie.

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