Today it seems that the following rules governs the permissions of sequences:
SELECT - allow you to select * from seq_name;
INSERT - no effect
UPDATE - allows nextval, setval - and yes implicitly currval
DELETE - no effect
I suggest nextval is moved into the insert permission as this is quite natural - normally you only need to call nextval when you insert a new value into a table. I think this issue is important because setting the sequence to a value lower than the max value in a table will cause errors for other users.
Aasmund Midttun Godal
aasmund(at)godal(dot)com - http://www.godal.com/
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