Re: a funnel by any other name

On 22 September 2015 at 20:34, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Tue, Sep 22, 2015 at 10:34 AM, Simon Riggs <simon(at)2ndquadrant(dot)com>
> wrote:
> > Robert, thanks for asking. We'll be stuck with these words for some time,
> > user visible via EXPLAIN so this is important.
>
> I agree, thanks for taking an interest.
>
> > The main operations are the 3 mentioned by Nicolas:
> > 1. Send data from many to one - which has subtypes for Unsorted, Sorted
> and
> > Evenly balanced (but unsorted)
> > 2. Send data from one process to many
> > 3. Send data from many to many
> >
> > My preferences for this would be
> > 1. Gather (but not Gather Motion) e.g. Gather, Gather Sorted
> > 2. Scatter (since Broadcast only makes sense in the context of a
> distributed
> > query, it sounds weird for intra-node query)
> > 3. Redistribution - which implies the description of how we spread data
> > across nodes is "Distribution" (or DISTRIBUTED BY)
>
> "Scatter" isn't one of the things that I mentioned in my original
> email. Not sure where we'd use that, although there might be
> somewhere.

Understood. Thought it best to cover all the phrases we'll use in the
future now in one discussion.

> > For 3 we should definitely use Redistribute, since this is what Teradata
> has
> > been calling it for 30 years, which is where Greenplum got it from.
>
> That's a reasonable option. We can bikeshed it some more when we get that
> far.

Sure

> > For 1, Gather makes most sense.
>
> Yeah, I'm leaning that way myself. Amit argued for "Parallel Gather"
> but I think that's overkill. There can't be a non-parallel gather,
> and long names are a pain.

Agreed

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
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