Robert Haas <robertmh...@gmail.com> writes: > The currently-committed code generates paths where nested loops and > hash joins get pushed beneath the Gather node, but does not generate > paths where merge joins have been pushed beneath the Gather node. And > the reason I didn't try to generate those paths is because I believe > they will almost always suck.
That's a perfectly reasonable engineering judgment (and especially so for a first release). What I'd really like to see documented is how that conclusion is related, or not, to the rules about how path nodes should be decorated with parallel_safe, parallel_degree, etc annotations. The existing documentation is barely adequate to explain what those fields mean for primitive scan nodes; it's impossible for anyone but you to know what they are supposed to mean for joins and higher-level nodes. regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers