Horton

Re: Eager aggregation, take 3

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
Cc: 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, Robert Haas <robertmhaas@gmail.com>
Date: 2024-10-31T12:15:58Z
Lists: pgsql-hackers 
hi.
still trying to understand v13. found a bug.

minimum test :
drop table if exists t1, t2;
CREATE TABLE t1 (a int, b int, c int);
CREATE TABLE t2 (a int, b int, c int);
SET enable_eager_aggregate TO on;
explain(costs off, settings) SELECT avg(t2.a), t1.c FROM t1 JOIN t2 ON
t1.b = t2.b GROUP BY t1.c having grouping(t1.c) > 0;


create_agg_clause_infos
    foreach(lc, tlist_exprs)
    {
        Expr       *expr = (Expr *) lfirst(lc);
        if (IsA(expr, GroupingFunc))
            return;
    }
    if (root->parse->havingQual != NULL)
    {
        List       *having_exprs;
        having_exprs = pull_var_clause((Node *) root->parse->havingQual,
                                       PVC_INCLUDE_AGGREGATES |
                                       PVC_RECURSE_PLACEHOLDERS);
        if (having_exprs != NIL)
        {
            tlist_exprs = list_concat(tlist_exprs, having_exprs);
            list_free(having_exprs);
        }
    }

havingQual can have GroupingFunc.
if that happens, then segmentation fault.

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