Subject Re: [firebird-support] How many RAM does FB can manage?
Author Ann W. Harrison
kokok_kokok wrote:
> I am working on a large project, with millions of records and over
> 60GB in database size.
> Now, I am specificing the hardware required, I have read that FB uses
> up to 2GB of RAM. Is it true? What RAM is recommended for a large
> database keeping in mind that RAM cost is not significant?

Firebird was designed when a big machine had a couple of megs of
memory, so it has very low memory requirements. For a long time,
there was a penalty for using too much memory for the pages cache -
a bad algorithm in the flush code, but that's no longer there.

The amount of useful cache depends on the size of the normal working
set ... For example, if you normally just use the last day's worth
of data, you need less. If you regularly run queries against the
whole 60GB, you can use more. I'd order as much as fits on the
machine and figure I could move it to another machine if the
application turned out to run with less memory.

Firebird also uses memory to keep metadata, transaction state,
the lock table, compiled queries, and other good and useful
stuff, but all that is pretty small...