[AccessD] Access 2010 Beta - Calculated fields

Seems to distort the math too.

Double 33 is 66 in A2k3.  :)

Max


-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Asger Blond
Sent: 12 February 2010 23:22
To: 'Access Developers discussion and problem solving'
Subject: [AccessD] Access 2010 Beta - Calculated fields

Hi group,
Just downloaded the Access 2010 Beta and observed that a new data type for
fields was added: Calculated.
Knowing that this kind of denormalized field has been around in SQL Server
for some time I thought it would be the same in A2K10.
Well: It's not!
In SQL Server a calculated field is not persisted, it's just a convenient
way to pre-announce a calculation which will be used on the fly when
querying the table. You can in fact persist the calculated values in SQL
Server, but only if you create an index on the field - otherwise it's of
course not persisted.
So I was astonished in A2K10 that I didn't have a choice whether to index
this kind of field.
I then created a test db containing a table with two number-fields and one
million records. Size of the db: 33 GB. To check I copied the db to a new db
and added a calculated field to the table (trivial calculation: Field1 *
Field2). And guess what? The size of the new db was double up+: 72 GB.
So please: stick to your old practice creating calculations only in queries,
and don't ever use the new Calculated field type in Access 2010!

Asger


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