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While converting expressions in an upper-level plan node so that they reference Vars and expressions provided by the input plan node(s), don't convert plain Const items, even if there happens to be a matching Const in the input. It's silly to do so because a Var is more expensive to execute than a Const. Moreover, converting can fool ExecCheckPlanOutput's check that an insert or update query inserts nulls into dropped columns, leading to "query provides a value for a dropped column" errors during INSERT or UPDATE on a table with a dropped column. We could solve this by making that check more complicated, but I don't see the point; this fix should save a marginal number of cycles, and it also makes for less messy EXPLAIN output, as shown by the ensuing regression test result changes. Per report from Pavel Hanák. I have not incorporated a test case based on that example, as there doesn't seem to be a simple way of checking this in isolation without making a bunch of assumptions about other planner and SQL-function behavior. Back-patch to 9.6. This setrefs.c behavior exists much further back, but there is not currently reason to think that it causes problems before 9.6. Discussion: <83shraampf.fsf@is-it.eu>
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: http://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 http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.