Christian,

>> what's the PLAN? Does it include a SORT clause?

CG> I have attached the plans at the end of this message.
CG> And yes, they contain a SORT clause.

you could try to remove your ORDER BY clauses to see if the problem
really has to do with sorting. Then your next step would be to try and
make up a reproducible case unless someone in the knows in
firebird-support or firebird-devel has any other suggestion ready.

>> Doesn't look to be IBO-related.

CG> This is why I had posted this issue to the firebird-support list,
CG> but people seem to have different opinions on this.

It's difficult to say. The memory growth on the server could be due by
a combination of a server bug and erratic client behaviour, but it
doesn't seem much realistic to me.

Ciao
--
Nando Dessena
http://www.flamerobin.org