Function scanNameSpaceForRefname

src/backend/parser/parse_relation.c:185–215

* Search the query's table namespace for an item matching the * given unqualified refname. Return the nsitem if a unique match, or NULL * if no match. Raise error if multiple matches. * * Note: it might seem that we shouldn't have to worry about the possibility * of multiple matches; after all, the SQL standard disallows duplicate table * aliases within a given SELECT level. Historically,

 * reference to "x".
 */
static ParseNamespaceItem *
scanNameSpaceForRefname(ParseState *pstate, const char *refname, int location)
{
	ParseNamespaceItem *result = NULL;
	ListCell   *l;

	foreach(l, pstate->p_namespace)
	{
		ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(l);

		/* Ignore columns-only items */
		if (!nsitem->p_rel_visible)
			continue;
		/* If not inside LATERAL, ignore lateral-only items */
		if (nsitem->p_lateral_only && !pstate->p_lateral_active)
			continue;

		if (strcmp(nsitem->p_names->aliasname, refname) == 0)
		{
			if (result)
				ereport(ERROR,
						(errcode(ERRCODE_AMBIGUOUS_ALIAS),
						 errmsg("table reference \"%s\" is ambiguous",
								refname),
						 parser_errposition(pstate, location)));
			check_lateral_ref_ok(pstate, nsitem, location);
			result = nsitem;
		}
	}
	return result;
}

/*
 * Search the query's table namespace for a relation item matching the