Recognize functional dependency on primary keys. This allows a table's

other columns to be referenced without listing them in GROUP BY, so long as
the primary key column(s) are listed in GROUP BY.

Eventually we should also allow functional dependency on a UNIQUE constraint
when the columns are marked NOT NULL, but that has to wait until NOT NULL
constraints are represented in pg_constraint, because we need to have
pg_constraint OIDs for all the conditions needed to ensure functional
dependency.

Peter Eisentraut, reviewed by Alex Hunsaker and Tom Lane

src/include/nodes/parsenodes.h

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.433 2010/07/25 23:21:22 rhaas Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.434 2010/08/07 02:44:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -146,6 +146,9 @@ typedef struct Query
 
 	Node	   *setOperations;	/* set-operation tree if this is top level of
 								 * a UNION/INTERSECT/EXCEPT query */
+
+	List	   *constraintDeps;	/* a list of pg_constraint OIDs that the query
+								 * depends on to be semantically valid */
 } Query;