Function check_lateral_ref_ok

src/backend/parser/parse_relation.c:471–492

* Complain if a namespace item is currently disallowed as a LATERAL reference. * This enforces both SQL:2008's rather odd idea of what to do with a LATERAL * reference to the wrong side of an outer join, and our own prohibition on * referencing the target table of an UPDATE or DELETE as a lateral reference * in a FROM/USING clause. * * Note: the pstate should be the same query level the nsit

 * Convenience subroutine to avoid multiple copies of a rather ugly ereport.
 */
static void
check_lateral_ref_ok(ParseState *pstate, ParseNamespaceItem *nsitem,
					 int location)
{
	if (nsitem->p_lateral_only && !nsitem->p_lateral_ok)
	{
		/* SQL:2008 demands this be an error, not an invisible item */
		RangeTblEntry *rte = nsitem->p_rte;
		char	   *refname = nsitem->p_names->aliasname;

		ereport(ERROR,
				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
				 errmsg("invalid reference to FROM-clause entry for table \"%s\"",
						refname),
				 (pstate->p_target_nsitem != NULL &&
				  rte == pstate->p_target_nsitem->p_rte) ?
				 errhint("There is an entry for table \"%s\", but it cannot be referenced from this part of the query.",
						 refname) :
				 errdetail("The combining JOIN type must be INNER or LEFT for a LATERAL reference."),
				 parser_errposition(pstate, location)));
	}
}

/*
 * Given an RT index and nesting depth, find the corresponding