Re: parallel mode and parallel contexts

On Wed, Jan 7, 2015 at 3:54 PM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> wrote:
> Agreed, I was more concerned with calls to nextval(), which don't seem to be
> prevented in parallel mode?

It looks prevented:

/*
* Forbid this during parallel operation because, to make it work,
* the cooperating backends would need to share the backend-local cached
* sequence information. Currently, we don't support that.
*/
PreventCommandIfParallelMode("nextval()");

> I was more thinking about all the add-on pl's like pl/ruby. But yeah, I
> don't see that there's much we can do if they're not using SPI.

Actually, there is: it's forbidden at the layer of heap_insert(),
heap_update(), heap_delete(). It's hard to imagine anyone trying to
modify the database as a lower level than that.

--
Robert Haas
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