Re: IMMUTABLE and PARALLEL SAFE function markings - Mailing list pgsql-hackers

From Robert Haas
Subject Re: IMMUTABLE and PARALLEL SAFE function markings
Date
Msg-id CA+TgmoY45Mb6d98SkssBbodpwqyoBPFC4igKCvKx06xcy7JDCA@mail.gmail.com
Whole thread Raw
In response to Re: IMMUTABLE and PARALLEL SAFE function markings  (Vik Fearing <vik.fearing@2ndquadrant.com>)
List pgsql-hackers
On Mon, Nov 26, 2018 at 7:47 PM Vik Fearing <vik.fearing@2ndquadrant.com> wrote:
> > I'm way less inclined to buy into the idea that it MUST be wrong, though.
> > Immutability is a promise about result stability and lack of side effects,
> > but it is not a promise about implementation details.  There could be an
> > implementation reason not to run something in a parallel worker.  Off the
> > top of my head, a possible example is "it's written in plfoo which hasn't
> > yet been made to work correctly in parallel workers".
>
> Now, see, that is an actual argument for making a difference.  The other
> arguments in this thread were not, so say I.

I agree with you that Tom is the first person to make a real argument
for distinguishing these two things.  And I think his argument is a
good one.  I suspect that there are other cases too.  I don't think
there are all that many cases, but I think they exist.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


pgsql-hackers by date:

Previous
From: Andres Freund
Date:
Subject: Re: Remove Deprecated Exclusive Backup Mode
Next
From: Robert Haas
Date:
Subject: Re: IMMUTABLE and PARALLEL SAFE function markings