Re: [RFC][PATCH] wal decoding, attempt #2 - Design Documents (really attached)

On Monday, October 15, 2012 04:54:20 AM Robert Haas wrote:
> On Thu, Oct 11, 2012 at 3:15 AM, Heikki Linnakangas
> 
> <hlinnakangas@vmware.com> wrote:
> > IMHO that's a good thing, and I'd hope this new logical replication to
> > live outside core as well, as much as possible. But whether or not
> > something is in core is just a political decision, not a reason to
> > implement something new.
> > 
> > If the only meaningful advantage is reducing the amount of WAL written, I
> > can't help thinking that we should just try to address that in the
> > existing solutions, even if it seems "easy to solve at a first glance,
> > but a solution not using a normal transactional table for its log/queue
> > has to solve a lot of problems", as the document says. Sorry to be a
> > naysayer, but I'm pretty scared of all the new code and complexity these
> > patches bring into core.

> I do not personally believe that a WAL decoding solution adequate to
> drive logical replication can live outside of core, at least not
> unless core exposes a whole lot more interface than we do now, and
> probably not even then.  Even if it could, I don't see the case for
> making every replication solution reinvent that wheel.  It's a big
> wheel to be reinventing, and everyone needs pretty much the same
> thing.
Unsurprisingly I aggree.

> That having been said, I have to agree that the people working on this
> project seem to be wearing rose-colored glasses when it comes to the
> difficulty of implementing a full-fledged solution in core. 
That very well might be true. Sometimes rose-colored glasses can be quite 
productive in getting something started...

Note at this point were only want wal decoding, background workers and related 
things to get integrated...

Greetings,

Andres
-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services