Function addTargetToGroupList

src/backend/parser/parse_clause.c:3717–3763

* addTargetToGroupList * If the given targetlist entry isn't already in the SortGroupClause * list, add it to the end of the list, using default sort/group * semantics. * * This is very similar to addTargetToSortList, except that we allow the * case where only a grouping (equality) operator can be found, and that * the TLE is considered "already in the list" if it appears there with any

 * Returns the updated SortGroupClause list.
 */
static List *
addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
					 List *grouplist, List *targetlist, int location)
{
	Oid			restype = exprType((Node *) tle->expr);

	/* if tlist item is an UNKNOWN literal, change it to TEXT */
	if (restype == UNKNOWNOID)
	{
		tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr,
										 restype, TEXTOID, -1,
										 COERCION_IMPLICIT,
										 COERCE_IMPLICIT_CAST,
										 -1);
		restype = TEXTOID;
	}

	/* avoid making duplicate grouplist entries */
	if (!targetIsInSortList(tle, InvalidOid, grouplist))
	{
		SortGroupClause *grpcl = makeNode(SortGroupClause);
		Oid			sortop;
		Oid			eqop;
		bool		hashable;
		ParseCallbackState pcbstate;

		setup_parser_errposition_callback(&pcbstate, pstate, location);

		/* determine the eqop and optional sortop */
		get_sort_group_operators(restype,
								 false, true, false,
								 &sortop, &eqop, NULL,
								 &hashable);

		cancel_parser_errposition_callback(&pcbstate);

		grpcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
		grpcl->eqop = eqop;
		grpcl->sortop = sortop;
		grpcl->nulls_first = false; /* OK with or without sortop */
		grpcl->hashable = hashable;

		grouplist = lappend(grouplist, grpcl);
	}

	return grouplist;
}

/*
 * assignSortGroupRef