I think, the main problem is the following: all of the user are autheticated in the psql with the same username, and the thing, that you've mentioned, the locks (I will talk with the programmer, or create new users in the psql, and modify the ODBC settings at the client side). How can I setup a shorter time period for the idle time or less lock time?
> After the settings in the postgresql.conf our system is much faster, and no > more error messages in the postgres.log, but If I try to drop a table, or > add a new one, our system is stopping, until I kill the process, which is > dropping or adding a table.
you are almost certainly waiting on a lock. check pg_locks for ungranted locks and pg_stat_activity for idle/long running transactions. If you ever find yourself having to bump max_connections again, it is almost certainly a good idea to investigate a connection pooler like pgbouncer.
