Subject Re: [firebird-support] Char(20) vs Int64 for PrimarKey?
Author sugi
> Most of our tables are moderate size with a few tables around 500,000
> to 1 million records.
> ... snip ...
> What are most people using for PK's?
I don't know about 'most people', but i'm sticking with plain integer
(32bit) for now. The main reason is that my development environment and
data-access component might have problems dealing with bigints or int64
datatypes, due to some obscure ms-variant problem.

If your front-end tools can handle it, go with bigint.