--- /dev/null
+--
+-- Sanity checks for common errors in making pg_operator table.
+-- None of the SELECTs here should ever find any matching entries,
+-- so the expected output is easy to maintain ;-).
+-- A test failure indicates someone messed up an entry in pg_operator.h.
+--
+-- NB: run this test earlier than the create_operator test, because
+-- that test creates some bogus operators...
+--
+
+-- Look for bogus data types.
+
+SELECT p1.oid, p1.* FROM pg_operator AS p1
+WHERE p1.oprleft != 0 AND NOT EXISTS(SELECT * FROM pg_type AS t1 WHERE t1.oid = p1.oprleft);
+
+SELECT p1.oid, p1.* FROM pg_operator AS p1
+WHERE p1.oprright != 0 AND NOT EXISTS(SELECT * FROM pg_type AS t1 WHERE t1.oid = p1.oprright);
+
+SELECT p1.oid, p1.* FROM pg_operator AS p1
+WHERE p1.oprresult != 0 AND NOT EXISTS(SELECT * FROM pg_type AS t1 WHERE t1.oid = p1.oprresult);
+
+-- Look for dangling links to other operators.
+
+SELECT p1.oid, p1.* FROM pg_operator AS p1
+WHERE p1.oprcom != 0 AND NOT
+ EXISTS(SELECT * FROM pg_operator AS p2 WHERE p2.oid = p1.oprcom);
+
+SELECT p1.oid, p1.* FROM pg_operator AS p1
+WHERE p1.oprnegate != 0 AND NOT
+ EXISTS(SELECT * FROM pg_operator AS p2 WHERE p2.oid = p1.oprnegate);
+
+SELECT p1.oid, p1.* FROM pg_operator AS p1
+WHERE p1.oprlsortop != 0 AND NOT
+ EXISTS(SELECT * FROM pg_operator AS p2 WHERE p2.oid = p1.oprlsortop);
+
+SELECT p1.oid, p1.* FROM pg_operator AS p1
+WHERE p1.oprrsortop != 0 AND NOT
+ EXISTS(SELECT * FROM pg_operator AS p2 WHERE p2.oid = p1.oprrsortop);
+
+-- FIXME: how can we test for a dangling OPRCODE value?
+
+-- Look for conflicting operator definitions (same names and input datatypes).
+
+SELECT p1.oid, p1.oprcode, p2.oid, p2.oprcode
+FROM pg_operator AS p1, pg_operator AS p2
+WHERE p1.oid != p2.oid AND
+ p1.oprname = p2.oprname AND
+ p1.oprkind = p2.oprkind AND
+ p1.oprleft = p2.oprleft AND
+ p1.oprright = p2.oprright;
+
+-- Look for commutative operators that don't commute.
+-- DEFINITIONAL NOTE: If A.oprcom = B, then x A y has the same result as y B x.
+-- We expect that B will always say that B.oprcom = A as well; that's not
+-- inherently essential, but it would be inefficient not to mark it so.
+
+SELECT p1.oid, p1.oprcode, p2.oid, p2.oprcode
+FROM pg_operator AS p1, pg_operator AS p2
+WHERE p1.oprcom = p2.oid AND
+ (p1.oprkind != 'b' OR
+ p1.oprleft != p2.oprright OR
+ p1.oprright != p2.oprleft OR
+ p1.oprresult != p2.oprresult OR
+ p1.oid != p2.oprcom);
+
+-- Look for negatory operators that don't agree.
+-- DEFINITIONAL NOTE: If A.oprnegate = B, then both A and B must yield
+-- boolean results, and (x A y) == ! (x B y), or the equivalent for
+-- single-operand operators.
+-- We expect that B will always say that B.oprnegate = A as well; that's not
+-- inherently essential, but it would be inefficient not to mark it so.
+-- NOTE hardwired assumption that type bool has OID 16.
+
+SELECT p1.oid, p1.oprcode, p2.oid, p2.oprcode
+FROM pg_operator AS p1, pg_operator AS p2
+WHERE p1.oprnegate = p2.oid AND
+ (p1.oprkind != p2.oprkind OR
+ p1.oprleft != p2.oprleft OR
+ p1.oprright != p2.oprright OR
+ p1.oprresult != 16 OR
+ p2.oprresult != 16 OR
+ p1.oid != p2.oprnegate);
+
+-- Look for sort operators that don't match.
+-- A sort link normally leads from an '='
+-- operator to the matching '<' operator.
+-- Sort links are not commutative.
+
+SELECT p1.oid, p1.oprcode, p2.oid, p2.oprcode
+FROM pg_operator AS p1, pg_operator AS p2
+WHERE p1.oprlsortop = p2.oid AND
+ (p1.oprname != '=' OR
+ p1.oprkind != 'b' OR p2.oprkind != 'b' OR
+ p1.oprleft != p2.oprleft OR
+ p1.oprright != p2.oprright OR
+ p1.oprresult != 16 OR
+ p2.oprresult != 16 OR
+ p1.oprrsortop = 0);
+
+SELECT p1.oid, p1.oprcode, p2.oid, p2.oprcode
+FROM pg_operator AS p1, pg_operator AS p2
+WHERE p1.oprrsortop = p2.oid AND
+ (p1.oprname != '=' OR
+ p1.oprkind != 'b' OR p2.oprkind != 'b' OR
+ p1.oprleft != p2.oprleft OR
+ p1.oprright != p2.oprright OR
+ p1.oprresult != 16 OR
+ p2.oprresult != 16 OR
+ p1.oprlsortop = 0);