| From: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | Michael Lewis <mlewis(at)entrata(dot)com>, Israel Brewster <ijbrewster(at)alaska(dot)edu>, PostgreSQL Mailing Lists <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Faster distinct query? |
| Date: | 2021-09-23 01:28:32 |
| Message-ID: | CAKFQuwZdBcBOi6mKnddeCjXjxXSmcLhdpiDSr+4Uuh+scmKwXg@mail.gmail.com |
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| Lists: | pgsql-general |
On Wednesday, September 22, 2021, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> I think writing the query in such a way
> that allows it to be parallelised is likely going to result in some
> quite good performance improvements. i.e:
>
Agreed, though if the query author needs to do that here we’ve violated the
spirit of the declarative SQL language. At first blush nothing about the
original query seems like it should be preventing parallelism. Each worker
builds its own distinct array then the final concatenation is made distinct.
David J.
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