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: 2024-05-20T08:12:49Z
Lists: pgsql-hackers

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Another rebase is needed after d1d286d83c.  Also I realized that the
partially_grouped_rel generated by eager aggregation might be dummy,
such as in query:

select count(t2.c) from t t1 join t t2 on t1.b = t2.b where false group by
t1.a;

If somehow we choose this dummy path with a Finalize Agg Path on top of
it as the final cheapest path (a very rare case), we would encounter the
"Aggref found in non-Agg plan node" error.  The v7 patch fixes this
issue.

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