Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation) - Mailing list pgsql-hackers

From Peter Geoghegan
Subject Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation)
Date
Msg-id CAH2-Wzn2rXNuL+wu2qCdknPYtkKCXN2bT=YVNBX9LA6JdHB7jw@mail.gmail.com
Whole thread Raw
In response to Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation)  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
List pgsql-hackers
On Wed, Jan 10, 2018 at 2:36 PM, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> I think "one at a time" is not the right way to interpret the affix.
> Rather, a "partitionwise join" is a join done "in the manner of
> partitions", that is, the characteristics of the partitions are
> considered when the join is done.
>
> I'm not defending the "leader-wise" term here, though, because I can't
> make sense of it, regardless of how I interpret the -wise affix.

I've already conceded the point, but fwiw "leader-wise" comes from the
idea of having a leader-wise space following concatenating worker
tapes (who have original/worker-wise space). We must apply an offset
to get from a worker-wise offset to a leader-wise offset.

This made more sense in an earlier version. I overlooked this during
recent self review.

-- 
Peter Geoghegan


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