Horton

Re: Add proper planner support for ORDER BY / DISTINCT aggregates

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Ronan Dunklau <ronan.dunklau@aiven.io>, Justin Pryzby <pryzby@telsasoft.com>, Pavel Luzanov <p.luzanov@postgrespro.ru>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org, Ranier Vilela <ranier.vf@gmail.com>
Date: 2022-11-09T01:58:53Z
Lists: pgsql-hackers

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On Tue, 8 Nov 2022 at 19:51, Richard Guo <guofenglinux@gmail.com> wrote:
> For unsorted paths, the original logic here is to explicitly add a Sort
> path only for the cheapest-total path.  This patch changes that and may
> add a Sort path for other paths besides the cheapest-total path.  I
> think this may introduce in some unnecessary path candidates.

Yeah, you're right. The patch shouldn't change that.  I've adjusted
the attached patch so that part works more like it did before.

v2 attached.

Thanks

David

Commits

  1. Don't presort ORDER BY/DISTINCT Aggrefs with volatile functions

  2. Add enable_presorted_aggregate GUC

  3. Remove pessimistic cost penalization from Incremental Sort

  4. Fix hypothetical problem passing the wrong GROUP BY pathkeys

  5. Remove unused fields from ExprEvalStep

  6. Improve performance of ORDER BY / DISTINCT aggregates

  7. Refactor function parse_subscription_options.