disabling constraints

I would like to be able to truncate all of the tables in a schema without worrying about FK constraints. I tried issuing a "SET CONSTRAINTS ALL DEFERRED" before truncating, but I still get constraint errors. Is there a way to do something like:

1) disable all constraints
2) truncate all tables
3) re-enable all constraints

?

In the slony project there is a procedure "altertableforreplication" that appears to do 1), but since it is updating pg_catalog tables directly, I don't want to cut/paste before I understand what it's doing!

Is there any "standard" way of doing this?

- DAP
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David Parker Tazz Networks (401) 709-5130