Обсуждение: Effect of too many columns

Greetings,

Is there any performance penalty of having too many columns in
a table in terms of read and write speeds.

To order to keep operational queries simple (avoid joins) we plan to
add columns in the main customer dimension table.

Adding more columns also means increase in concurrency in the table
as more and more applications will access the same table.

Any ideas if its better to split the table application wise or is it ok?



Regds
mallah.

On Mon, Apr 12, 2004 at 17:24:17 +0530,
  Rajesh Kumar Mallah <mallah@trade-india.com> wrote:
>
> Greetings,
>
> Is there any performance penalty of having too many columns in
> a table in terms of read and write speeds.
>
> To order to keep operational queries simple (avoid joins) we plan to
> add columns in the main customer dimension table.
>
> Adding more columns also means increase in concurrency in the table
> as more and more applications will access the same table.
>
> Any ideas if its better to split the table application wise or is it ok?

This is normally a bad idea. If you properly implement constraints in
what is effectively a materialized view, you might end up with a slower
system, depending on your mix of queries. (Generally updating will take
more resources.) So you probably want to test your new design under a
simulated normal load to see if it actually speeds things up in your
case before making the change.