Unmark 'hashable' operators that can't really be used for

hashjoins.  Extend opr_sanity regress test to help detect similar mistakes.

2 files changed, 12 insertions, 6 deletions

diff --git a/src/test/regress/expected/opr_sanity.out b/src/test/regress/expected/opr_sanity.out
index f044006daad..7b47da02f3c 100644
--- a/src/test/regress/expected/opr_sanity.out
+++ b/src/test/regress/expected/opr_sanity.out
@@ -135,10 +135,13 @@ oid|oprname
 QUERY: SELECT p1.oid, p1.oprname
 FROM pg_operator as p1
 WHERE p1.oprcanhash AND NOT
-    (p1.oprkind = 'b' AND p1.oprresult = 16 AND p1.oprcom != 0);
-oid|oprname
----+-------
-(0 rows)
+    (p1.oprkind = 'b' AND p1.oprresult = 16 AND p1.oprleft = p1.oprright AND
+     p1.oprname = '=' AND p1.oprcom = p1.oid);
+ oid|oprname
+----+-------
+1136|=      
+1137|=      
+(2 rows)
 
 QUERY: SELECT p1.oid, p1.oprcode, p2.oid, p2.oprcode
 FROM pg_operator AS p1, pg_operator AS p2
diff --git a/src/test/regress/sql/opr_sanity.sql b/src/test/regress/sql/opr_sanity.sql
index 63a24c7b53d..6beeef7eafa 100644
--- a/src/test/regress/sql/opr_sanity.sql
+++ b/src/test/regress/sql/opr_sanity.sql
@@ -132,12 +132,15 @@ WHERE (p1.oprleft = 0 and p1.oprkind != 'l') OR
     (p1.oprright = 0 and p1.oprkind != 'r') OR
     (p1.oprright != 0 and p1.oprkind = 'r');
 
--- Hash operators should be commutative binary ops returning bool.
+-- Hashing only works on simple equality operators "type = sametype",
+-- since the hash itself depends on the bitwise representation of the type.
+-- Check that allegedly hashable operators look like they might be "=".
 
 SELECT p1.oid, p1.oprname
 FROM pg_operator as p1
 WHERE p1.oprcanhash AND NOT
-    (p1.oprkind = 'b' AND p1.oprresult = 16 AND p1.oprcom != 0);
+    (p1.oprkind = 'b' AND p1.oprresult = 16 AND p1.oprleft = p1.oprright AND
+     p1.oprname = '=' AND p1.oprcom = p1.oid);
 
 -- Look for conflicting operator definitions (same names and input datatypes).