On Dec 4, 9:56 pm, M. wrote:
My main question is: are there negative aspects associated with using a
primary key based on data fields versus using a primary key based on an
artificial primary key as generated with an autonumber field? In both cases
the autonumber field would be used for defining relations between tables.

As a guess: for reasons of optimization because PRIMARY KEY determines
physical ordering on disk (clustering). See:

Microsoft Jet 3.5 Performance Overview and Optimization Techniques
http://msdn.microsoft.com/archive/de...baseEngine.asp

"From a performance perspective, there are many reasons to frequently
compact a database. One reason is that compacting will create a new
database that stores all table rows in a contiguous order. If a
primary key or unique index is defined, the rows will be sorted in
order of the primary key or unique index. This allows Microsoft Jet to
take full advantage of its read-ahead cache and also reduces disk I/O
when doing sequential scans of a table."

Put the other way around, assigning the table's PRIMARY KEY
designation to the Autonumber column could have a negative impact on
the performance of queries which use a sequential scan on a table e.g.
using the BETWEEN keyword in SQL code.

Jamie.

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