xchris wrote:
>
> Let's suppose i need to add an info about addresses (which includes
> country,city,cap....etc etc).
> Addresses can vary from 1 to 20 entries..
>
> Talking about performance is it better to include a list of addresses in
> TABLE A or is it better to create an external TABLE B?
Don't optimise before you have to.
Do the addresses belong in "A"? If so, put them there. On the other
hand, if you want items in "A" to have more than one address, or to
share addresses then clearly you will want a separate address table.
It's difficult to say more without a clear example of your requirements.
Even if you choose to alter your design for performance reasons, you
should make sure you run tests with realistic workloads and hardware.
But first, trust PG to do its job and design your database according to
the problem requirements.
--
Richard Huxton
Archonet Ltd