Horton

Re: Eager aggregation, take 3

Tender Wang <tndrwang@gmail.com>

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From: Tender Wang <tndrwang@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Paul George <p.a.george19@gmail.com>, Andy Fan <zhihuifan1213@163.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org, Robert Haas <robertmhaas@gmail.com>
Date: 2024-08-28T03:57:12Z
Lists: pgsql-hackers 
Richard Guo <guofenglinux@gmail.com> 于2024年8月21日周三 15:11写道：

> On Fri, Aug 16, 2024 at 4:14 PM Richard Guo <guofenglinux@gmail.com>
> wrote:
> > I had a self-review of this patchset and made some refactoring,
> > especially to the function that creates the RelAggInfo structure for a
> > given relation.  While there were no major changes, the code should
> > now be simpler.
>
> I found a bug in v10 patchset: when we generate the GROUP BY clauses
> for the partial aggregation that is pushed down to a non-aggregated
> relation, we may produce a clause with a tleSortGroupRef that
> duplicates one already present in the query's groupClause, which would
> cause problems.
>
> Attached is the updated version of the patchset that fixes this bug
> and includes further code refactoring.
>

Rectenly, I do some benchmark tests, mainly on tpch and tpcds.
tpch tests have no plan diff, so I do not continue to test on tpch.
tpcds(10GB) tests have 22 plan diff as below:
4.sql, 5.sql, 8.sql,11.sql,19.sql,23.sql,31.sql,
33.sql,39.sql,45.sql,46.sql,47.sql,53.sql,
56.sql,57.sql,60.sql,63.sql,68.sql,74.sql,77.sql,80.sql,89.sql

I haven't look all of them. I just pick few simple plan test(e.g. 19.sql,
45.sql).
For example, 19.sql, eager agg pushdown doesn't get large gain, but a little
performance regress.

I will continue to do benchmark on this feature.

[1] https://github.com/tenderwg/eager_agg

-- 
Tender Wang

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