f5635c2786
Commit c8d2f68cc taught expr_is_nonnullable() to treat a DistinctExpr
as never returning NULL. That is wrong: when neither input is NULL,
the result is NULL if the underlying equality operator returns NULL,
which nothing forbids. This could lead to wrong query results.
To fix, remove the DistinctExpr case, along with its test case.
While at it, test the relkind before calling has_subclass() in
var_is_nonnullable(), to avoid a useless syscache lookup for
partitioned tables.
Reported-by: Robert Haas <robertmhaas@gmail.com>
Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CA+TgmoaLcsmc9weJr1yo1X1SwZJX1t4XXHj0SJzH8XztmN9Hdg@mail.gmail.com
Backpatch-through: 19
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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