d376ab570e
The code carelessly modified mtstate->ps.plan->targetlist, which it's not supposed to do. Fortunately, there's not really any need to do that because the planner already set up a perfectly acceptable targetlist for the plan node. We just need to remove the erroneous assignments and update some relevant comments. As it happens, the erroneous assignments caused the targetlist to point to a different part of the source plan tree, so that there isn't really a risk of the pointer becoming dangling after executor termination. The only visible effect of this change we can find is that EXPLAIN will show upper references to the ModifyTable's output expressions using different variables. Formerly it showed Vars from the first target relation that survived executor-startup pruning. Now it always shows such references using the first relation appearing in the planner output, independently of what happens during executor pruning. On the whole that seems like a good thing. Also make a small tweak in ExplainPreScanNode to ensure that the first relation will receive a refname assignment in set_rtable_names, even if it got pruned at startup. Previously the Vars might be shown without any table qualification, which is confusing in a multi-table query. I considered back-patching this, but since the bug doesn't seem to have any really terrible consequences in existing branches, it seems better to not change their EXPLAIN output. It's not too late for v18 though, especially since v18 already made other changes in the EXPLAIN output for these cases. Reported-by: Tom Lane <tgl@sss.pgh.pa.us> Author: Andres Freund <andres@anarazel.de> Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/213261.1747611093@sss.pgh.pa.us
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.
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