Function build_implied_join_equality

src/backend/optimizer/plan/initsplan.c:2792–2836

* build_implied_join_equality --- build a RestrictInfo for a derived equality * * This overlaps the functionality of process_implied_equality(), but we * must not push the RestrictInfo into the joininfo tree. * * Note: this function will copy item1 and item2, but it is caller's * responsibility to make sure that the Relids parameters are fresh copies * not shared with other uses. * * Note

 * caller's responsibility that left_ec/right_ec be set as necessary.
 */
RestrictInfo *
build_implied_join_equality(PlannerInfo *root,
							Oid opno,
							Oid collation,
							Expr *item1,
							Expr *item2,
							Relids qualscope,
							Relids nullable_relids,
							Index security_level)
{
	RestrictInfo *restrictinfo;
	Expr	   *clause;

	/*
	 * Build the new clause.  Copy to ensure it shares no substructure with
	 * original (this is necessary in case there are subselects in there...)
	 */
	clause = make_opclause(opno,
						   BOOLOID, /* opresulttype */
						   false,	/* opretset */
						   copyObject(item1),
						   copyObject(item2),
						   InvalidOid,
						   collation);

	/*
	 * Build the RestrictInfo node itself.
	 */
	restrictinfo = make_restrictinfo(root,
									 clause,
									 true,	/* is_pushed_down */
									 false, /* outerjoin_delayed */
									 false, /* pseudoconstant */
									 security_level,	/* security_level */
									 qualscope, /* required_relids */
									 NULL,	/* outer_relids */
									 nullable_relids);	/* nullable_relids */

	/* Set mergejoinability/hashjoinability flags */
	check_mergejoinable(restrictinfo);
	check_hashjoinable(restrictinfo);
	check_memoizable(restrictinfo);

	return restrictinfo;
}


/*