Re: BUG #16714: INSERT ON CONFLICT DO UPDATE fails to infer constraint if it's not at top-level partition

branch: REL_11_STABLE

src/backend/executor/nodeModifyTable.c:

         * BEFORE ROW INSERT Triggers.
         *
         * Note: We fire BEFORE ROW TRIGGERS for every attempted insertion in an
         * INSERT ... ON CONFLICT statement.  We cannot check for constraint
         * violations before firing these triggers, because they can change the
         * values to insert.  Also, they can run arbitrary user-defined code with
         * side-effects that we can't cancel by just not inserting the tuple.
         */

Still not the place where ON CONFLICT could be validated on per-row basis?