Re: Patch to add support of "IF NOT EXISTS" to others "CREATE" statements

On Tue, Apr 1, 2014 at 10:03 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I'm willing to bend that to the extent of saying that COR leaves in place
> subsidiary properties that you might add *with additional statements* ---
> for example, foreign keys for a table, or privilege grants for a role.
> But the properties of the role itself have to be predictable from the COR
> statement, or it's useless.

+1.

>> Where this is a bit more interesting is in the case of sequences, where
>> resetting the sequence to zero may cause further inserts into an
>> existing table to fail.
>
> Yeah.  Sequences do have contained data, which makes COR harder to define
> --- that's part of the reason why we have CINE not COR for tables, and
> maybe we have to do the same for sequences.  The point being exactly
> that if you use CINE, you're implicitly accepting that you don't know
> the ensuing state fully.

Yeah.  I think CINE is more sensible than COR for sequences, for
precisely the reason that they do have contained data (even if it's
basically only one value).

-- 
Robert Haas
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