Andrew,

> As I see now almost all RAM is unused, but Firebird create
> huge temp files during
> heavy "selects". It is so far to start swapping.

FB uses RAM to cache database pages, but the sorting is always done
externally, i.e. on disk. Your heavy "selects" are obviously prepared with
SORT plans, so the engine must sort the intermediate or final result sets to
complete your requests, hence you see huge temporary sort files. This
process isn't related to the internal cache manager.

> Should I create RAM disk for temp files?

Yes, it's usual practice.


Dmitry