Richard Guo
ffeda04259
Eager aggregation pushes a partial aggregate down to a base or join relation, to be finalized after that relation is joined with the rest of the query. eager_aggregation_possible_for_relation() already refuses to do this for a relation on the nullable side of an outer join, but it failed to also refuse it for a relation on the inner side of a semijoin or antijoin. Such a join does not emit its inner rows, so a partial aggregate computed on the inner side does not survive the join and cannot be combined by the final aggregation. This can happen only for an aggregate that references no table column, such as count(*): it is considered computable on any relation, including the inner one, whereas an aggregate that references a column is anchored to the outer side and never reaches the inner relation. The existing outer-join check did not catch this because it consults nulling_relids, which only tracks joins that null-extend their inner side. Semijoins and antijoins formed from EXISTS, IN, NOT EXISTS, or NOT IN sublinks do not null-extend and carry no ojrelid, so they are invisible to that check. Fix by additionally rejecting any relation that includes inner-side relations of a semijoin or antijoin but not the join's outer side. Pushing a partial aggregate to the outer side of such a join, grouped by the join key, remains valid and is still allowed. Reported-by: Radim Marek <radim@boringsql.com> Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Tender Wang <tndrwang@gmail.com> Discussion: https://postgr.es/m/CAJgoLk+d_P5sKrx-SZt01Acm_j0QnWn6aKJzFJ=waRu_3C8AoQ@mail.gmail.com
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
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