Horton

Re: Eager aggregation, take 3

Richard Guo <guofenglinux@gmail.com>

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From: Richard Guo <guofenglinux@gmail.com>
To: Robert Haas <robertmhaas@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: 2024-11-12T00:27:24Z
Lists: pgsql-hackers 
On Tue, Nov 12, 2024 at 1:30 AM Robert Haas <robertmhaas@gmail.com> wrote:
> 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.
>
> Unfortunately, I don't know what you mean by grouped aggregation. I
> think of grouping and aggregation as synonyms, pretty much.

Ah, sorry for the confusion.  By "grouped aggregation", I mean
aggregation with a GROUP BY clause, where we produce a result row for
each group.  This contrasts with plain aggregation, where there is a
single result row for the whole query.

Thanks
Richard

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