On Wed, May 24, 2023 at 08:37:45AM +1200, David Rowley wrote:
> On Mon, 22 May 2023 at 07:05, Jonathan S. Katz <jkatz@postgresql.org> wrote:
> > * Parallel execution of queries that use `FULL` and `OUTER` joins
>
> I think this should be `RIGHT` joins rather than `OUTER` joins.
>
> LEFT joins have been parallelizable I think for a long time now.
Well, since we can swap left/right easily, why would we not have just
have swappted the tables and done the join in the past? I think there
are two things missing in my description.
First, I need to mention parallel _hash_ join. Second, I think this
item is saying that the _inner_ side of a parallel hash join can be an
OUTER or FULL join. How about?
Allow hash joins to be parallelized where the inner side is
processed as an OUTER or FULL join (Melanie Plageman, Thomas Munro)
In this case, the inner side is the hashed side.
--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com
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