On 22 September 2015 at 20:34, Robert Haas <robertmh...@gmail.com> wrote:
> On Tue, Sep 22, 2015 at 10:34 AM, Simon Riggs <si...@2ndquadrant.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/> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
