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SubPlan nodes are typically built very early, before any RelOptInfos have been constructed for the parent query level. As a result, the simple_rel_array in the parent root has not yet been initialized. Currently, during cost estimation of a SubPlan's testexpr, we may call examine_variable() to look up statistical data about the expressions. This can lead to "no relation entry for relid" errors. To fix, pass root as NULL to cost_qual_eval() in cost_subplan(), since the root does not yet contain enough information to safely consult statistics. One exception is SubPlan nodes built for the initplans of MIN/MAX aggregates from indexes. In this case, having a NULL root is safe because testexpr will be NULL. Additionally, an initplan will by definition not consult anything from the parent plan. Backpatch to all supported branches. Although the reported call path that triggers this error is not reachable prior to v17, there's no guarantee that other code paths -- especially in extensions -- could not encounter the same issue when cost_qual_eval() is called with a root that lacks a valid simple_rel_array. The test case is not included in pre-v17 branches though. Bug: #19037 Reported-by: Alexander Lakhin <exclusion@gmail.com> Diagnosed-by: Tom Lane <tgl@sss.pgh.pa.us> Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/19037-3d1c7bb553c7ce84@postgresql.org Backpatch-through: 13
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. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.