How does PG know when a database is being accessed ?

Hi-

This is a problem I've observed on version 7.2.1.

I've been doing some setup work that involves dropping & recreating
databases a couple of times and I've noticed that once in a while, I'll get
the "database is being accessed by other users" message, even after
restarting the postmaster. This of course prevents me from dropping the DB.

I'd expect to get this if I've killed a client connection and the postmaster
hasn't had time to notice that the connection is defunct, but I was
surprised that restarting the postmaster didn't clear out the connections.

A couple of hours later, I can drop the database with no problem, and I
haven't done anything in the meantime, so I presume that a cleanup process
has run & tidied things up.

How are connections tracked & why does a record of a defunct client process
seem to persist through a restart?

Thanks
   -Nick

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Nick Fankhauser

    nickf@doxpop.com  Phone 1.765.965.7363  Fax 1.765.962.9788
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