How can I stop a long running query

 I'm using Postgesql 7.1 and the jdbc driver jdbc7.1-1.1
 to talk to the database from java/swing application (jdk1.3.1) I

How can I stop a long running query?
The method cancel of class Statement seems working well,
but if I look the process status I see a postmaster process
running in background.

Thank you,
Angelo.

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Angelo Misto` - Osservatorio Astronomico di Brera
Via Bianchi 46. Merate, Lecco, Italy - Tel.: 039/9991159