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Re: Enforcing serial uniqueness?

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Martijn van Oosterhout wrote:

IIRC you can set the permissions on a sequence to allow nextval but not
setval.

I've not been able to find a way - granting UPDATE grants the use of both. Someone in the interactive docs ran into the same thing it seems:

http://www.postgresql.org/docs/8.0/interactive/sql-grant.html

"On my 8.0.1 installation, the select privilege on a sequence allowed the granted user to select from the sequence (i.e. the underlying table), but it did not allow nextval to be called. I had to also grant update to allow a user to user nextval. A problematic catch to this is that granting update also allows the granted user to use the setval function, which I consider a risk in this design."

Secondly, if you don't want people to be able to stuff with your ID
column, you could set a BEFORE INSERT trigger to overwrite whatever
they provide and a BEFORE UPDATE trigger to cancel any changes...

The problem is that to get the last inserted id, as far as I know, you need to select a value ahead of time via nextval, then insert with it. If I simply block/change all forced entries, I'll wind up blocking that, and won't know what id the row I just inserted got.

I believe there's a way to get the last row oid and use that to figure out what id was used, but I think that would require all clients to be PostgreSQL-specific, so isn't too useful if you don't control all the clients.



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