--- In firebird-support@yahoogroups.com, "kaczy27" <kaczy27@...> wrote:

>
> Hi,
>
> I am experiencing great performance loss of the database after
> rolling back transactions.
>
> I am doing quite a lot of those - in my testing module, which is
> roughly following this patter, 1. get prepared database, 2. start
> transaction 3. verify result correctnes, 4. rollback

By rollback, do you mean that you are deliberately calling rollback on
the transaction or simply abandoning the transaction. Abandoning the
transaction will leave the uncommitted record versions in the
database, and the next poor transaction that reads them is handed the
task of cleaning them up.

IIRC, then calling rollback will attempt to reverse every instruction
that was run which will take a lot longer than abandoning it, but
should not leave its mess around for someone else to clean up. There
is a limit to the size of this "undo log", or the server would run out
of memory. Once this limit is reached, a rollback simply abandons the
transaction. From memory the limit is somewhere around 5000 - 10000.
But from your description this is unlikely (although a lot can be done
in 2-3 minutes).

Until they are cleaned up, deleted records are still in all the
indices etc and so will still affect performance. You can try and run
a select count(*) from a table you have just run a lot of changes on
(after the rollback in a new transaction obviously) which will force
the cleanup to happen at that time.

You could alternatively run a sweep, or even just backup the database
will force garbage collection unless you choose otherwise.

Adam