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. > 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. > 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. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers