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When building a ForeignPath for a joinrel, if there's a possibility that EvalPlanQual will be executed, we must identify a suitable path for EPQ checks. If the outer or inner path of the chosen path is a ForeignPath representing a pushed-down join, we replace it with its fdw_outerpath to ensure that the EPQ check path consists entirely of local joins. If the chosen path is a MergePath, and its outer or inner path is a ForeignPath that is not already well enough ordered, the MergePath will have non-NIL outersortkeys or innersortkeys indicating the desired ordering to be created by an explicit Sort node. If we then replace the outer or inner path with its corresponding fdw_outerpath, and that path is already sufficiently ordered, we end up in an inconsistent state: the MergePath has non-NIL outersortkeys or innersortkeys, and its input path is already properly ordered. This inconsistency can result in an Assert failure or the addition of a redundant Sort node. To fix, check if the new outer or inner path of a MergePath is already properly sorted, and set its outersortkeys or innersortkeys to NIL if so. Bug: #18902 Reported-by: Nikita Kalinin <n.kalinin@postgrespro.ru> Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Tender Wang <tndrwang@gmail.com> Discussion: https://postgr.es/m/18902-71c1bed2b9f7c46f@postgresql.org
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.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.