> Hi Firebird lovers,
>
> I'm using Firebird 2.5 RC2, installed with default configuration on Windows.
>
> I've just tried to execute queries from threads for the first time.
>
> My conclusion is:
>
> If I execute two long running queries from different threads, but using the same database connection, those queries will be executed serially (i.e. the second query will wait executing until the first one has finished).

To be more precise - every API call on the same connection handle is serialized. You can fetch results almost in parallel, for example.

> If I execute two long running queries from different threads, and using different database connections, those queries will be executed simultaneously.
>
>
> Is this conclusion correct

Yes

> can I configure somehow that queries always can run simultaneously?

No

> Will this behaviour change with Firebird 3 (and if yes, in which way)?

No.

You always can create as many connections as you need, be simple ;)

Regards,
Vlad

PS Do you know another DBMS which can do what you want ?