Horton

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

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Richard Guo <guofenglinux@gmail.com>, Ronan Dunklau <ronan.dunklau@aiven.io>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Ranier Vilela <ranier.vf@gmail.com>
Date: 2022-08-02T13:19:39Z
Lists: pgsql-hackers 
David Rowley <dgrowleyml@gmail.com> writes:
> On Mon, 1 Aug 2022 at 03:49, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Likewise, it might be
>> better to fix DEFAULT_FDW_TUPLE_COST beforehand, to detangle what
>> the effects of that are.

> I chatted to Andres and Thomas about this last week and their view
> made me think it might not be quite as clear-cut as "just bump it up a
> bunch because it's ridiculously low" that I had in mind.  They
> mentioned about file_fdw and another one that appears to work on
> mmapped segments, which I don't recall if any names were mentioned.

Um ... DEFAULT_FDW_TUPLE_COST is postgres_fdw-specific, so I do not
see what connection some other FDW would have to it.

			regards, tom lane

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.