Tom Lane da8f3ebf30 Don't convert Consts into Vars during setrefs.c processing. ... 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>		2016-11-02 14:32:13 -04:00
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postgres_fdw.out	Don't convert Consts into Vars during setrefs.c processing.	2016-11-02 14:32:13 -04:00