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66c0185a3 gave the planner the ability to have union child queries provide the union planner with pre-sorted input so that UNION queries could be more efficiently implemented using Merge Append. That commit overlooked checking that the UNION target list and the union child target list's types all match. In some corner cases, this could result in the planner producing sorts using the sort operator of the top-level UNION's target list type rather than of the union child's target list's type. The implications of this range from silently working correctly, despite using the wrong sort operator all the way up to a segmentation fault. Here we fix by adjusting the planner so it makes no attempt to have the subquery produce pre-sorted results when the data type of the UNION target list and the types from the subquery target list don't match exactly. Backpatch to 17, where 66c0185a3 was introduced. Reported-by: Jason Smith <dqetool@126.com> Diagnosed-by: Tom Lane <tgl@sss.pgh.pa.us> Bug: 18764 Discussion: https://postgr.es/m/18764-63ad667ea26e877a%40postgresql.org Backpatch-through: 17
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/17/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/17/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/.