> We are using SuperServer on Windows. Tested with 2.5.2 / 2.5.7 / 2.5.8

>

> So I have some questions:

> Is it normal to have only one file for a GTT for all connections/transactions?

  Yes.

> Is normal to keep old data in the file when the GTT is declared with ON COMMIT DELETE ROWS and the transaction that inserted the data is committed and closed?

  Pages in this file are reused - in the same way as in regular database file

> Is it normal for the file to persist even if there are no active transactions at all? Only connections.

  Yes

> What we can do to avoid the huge disk usage by the temporary files in a situation where we always have active connections to the database?

  Look where you insert a lot of data into GTT's.

Note, GTT ON COMMIT PRESERVE ROWS keeps all data until disconnect.

If you DELETE it - it is not deleted physically until GC (same as in permament tables).

Regards,

Vlad