Horton

Re: Eager aggregation, take 3

Robert Haas <robertmhaas@gmail.com>

View thread View on postgr.es
From: Robert Haas <robertmhaas@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
Cc: jian he <jian.universality@gmail.com>, Tender Wang <tndrwang@gmail.com>, Paul George <p.a.george19@gmail.com>, Andy Fan <zhihuifan1213@163.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org
Date: 2024-12-04T14:38:30Z
Lists: pgsql-hackers 
On Sun, Nov 10, 2024 at 7:52 PM Richard Guo <guofenglinux@gmail.com> wrote:
> Hmm, currently we only consider grouped aggregation for eager
> aggregation.  For grouped aggregation, the window function's
> arguments, as well as the PARTITION BY expressions, must appear in the
> GROUP BY clause.  That is to say, the depname column in the first
> query, or the n column in the second query, will not be aggregated
> into the partial groups.  Instead, they will remain as they are as
> input for the WindowAgg nodes.  It seems to me that this ensures
> that we're good with window functions.  But maybe I'm wrong.

Returning to this point now that I understand what you meant by
grouped aggregation:

I still don't understand how you expect to be able to evaluate
functions like LEAD() and LAG() if any form of partial aggregation has
been done.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

Commits

  1. Fix eager aggregation for semi/antijoin inner rels

  2. Cover additional errors and corner conditions in repack.c

  3. Fix volatile function evaluation in eager aggregation

  4. Fix collation handling for grouping keys in eager aggregation

  5. Rename apply_at to apply_agg_at for clarity

  6. Fix comment in eager_aggregate.sql

  7. Remove unnecessary include of "utils/fmgroids.h"

  8. Implement Eager Aggregation

  9. Allow negative aggtransspace to indicate unbounded state size

  10. Add macros for looping through a List without a ListCell.

  11. Account for the effect of lossy pages when costing bitmap scans.

  12. Fix a thinko in join_is_legal: when we decide we can implement a semijoin