Horton

Re: Eager aggregation, take 3

Richard Guo <guofenglinux@gmail.com>

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From: Richard Guo <guofenglinux@gmail.com>
To: Andy Fan <zhihuifan1213@163.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org
Date: 2024-07-03T08:29:27Z
Lists: pgsql-hackers

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On Thu, Jun 13, 2024 at 4:07 PM Richard Guo <guofenglinux@gmail.com> wrote:
> I spent some time testing this patchset and found a few more issues.
> ...

> Hence here is the v8 patchset, with fixes for all the above issues.

I found an 'ORDER/GROUP BY expression not found in targetlist' error
with this patchset, with the query below:

create table t (a boolean);

set enable_eager_aggregate to on;

explain (costs off)
select min(1) from t t1 left join t t2 on t1.a group by (not (not
t1.a)), t1.a order by t1.a;
ERROR:  ORDER/GROUP BY expression not found in targetlist

This happens because the two grouping items are actually the same and
standard_qp_callback would remove one of them.  The fully-processed
groupClause is kept in root->processed_groupClause.  However, when
collecting grouping expressions in create_grouping_expr_infos, we are
checking parse->groupClause, which is incorrect.

The fix is straightforward: check root->processed_groupClause instead.

Here is a new rebase with this fix.

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