Ferda Brabenec wrote:

> Then our slowdowns don't seem to be garbage collection related.
>
> But if they were - if some transaction's activity triggers implicit
> garbage collection - does it significantly slow down only that
> GC-initiating transaction or does it noticably slow down all jobs
> being processed by the engine at given moment?

All jobs. In Firebird 1 and 1.5, there's a garbage collect thread,
separate from all other threads. When it runs, nothing else runs. When
it doesn't run, the database begins to look like New York City (or pick
your favorite large city) on the third day of a trash-collectors' strike.

>
> Is it possible to switch off implicit garbage collection and use
> ONLY sweep or gbak?

No. Without garbage collection, the whole system gets very very slow
because indexes have entries for old record versions that are no longer
relevant to running transactions. However, Firebird 2 behaves better in
this area, performing cooperative garbage collection when that's
convenient and leaving only the hard jobs for the garbage collect
thread. During the Vulcan merge, we'll have a time trial comparing the
mixed mode of V2 to the purely cooperative garbage collection of Vulcan.

Regards,


Ann