Re: The plan for FDW-based sharding

On Fri, Mar 4, 2016 at 11:17 PM, Craig Ringer <craig@2ndquadrant.com> wrote:
> If FDW-based sharding works, I'm happy enough, I have no horse in this race.
> If it doesn't work I don't much care either. What I'm worried about is it if
> works like partitioning using inheritance works - horribly badly, but just
> well enough that it's served as an effective barrier to doing anything
> better.
>
> That's what I want to prevent. Sharding that only-just-works and then stops
> us getting anything better into core.

That's a reasonable worry.  Thanks for articulating it so clearly.
I've thought about that issue and I admit it's both real and serious,
but I've sort of taken the attitude of saying, well, I don't know how
to solve that problem, but there's so much other important work that
needs to be done before we get to the point where that's the blocker
that solving that problem doesn't seem like the most important thing
right now.

I think your concern is
valid, and I share it.  But I just fundamentally believe that it's
better to enhance what we have than to start inventing totally new
abstractions.  The FDW API is *really* powerful, and getting more
powerful, and I just have a very hard time believing that starting
over will be better.  Somebody can do that if they like and I'm not
gonna get in the way, but if it's got problems that could have been
avoided by basing that same work on the FDW stuff we've already got, I
do plan to point that out.