Nico,
the Oldest Active Transaction is the first started transaction that is
still running. IB has to keep record versions for it's tables for each
changed record since the OAT so that it can get the correct value for the
correct transaction (the values of the fields in record x for transaction a
may differ from the values of the fields in record x for transaction b if
the value was changed and committed between the start of transaction a and
b). If there's been too many changes since the start of the OAT, the server
takes a long time in responding. Hence, the OAT is something to check if
your programs seems to take longer and longer time to execute and the
problems only get solved by restarting the IB server.

Set

At 12:44 06.04.2001 +0200, you wrote:

>Set,
>
> I must be a dummy one maybe , :-), I saw already a lot of messages
>here about OAT, but until now, I don't understand a single bit of it.
>
>Nico