Fix DROP OPERATOR to reset oprcom/oprnegate links to the dropped operator.

This avoids leaving dangling links in pg_operator; which while fairly
harmless are also unsightly.

While we're at it, simplify OperatorUpd, which went through
heap_modify_tuple for no very good reason considering it had already made
a tuple copy it could just scribble on.

Roma Sokolov, reviewed by Tomas Vondra, additional hacking by Robert Haas
and myself.

src/test/regress/expected/drop_operator.out

@@ -0,0 +1,61 @@
+CREATE OPERATOR === (
+        PROCEDURE = int8eq,
+        LEFTARG = bigint,
+        RIGHTARG = bigint,
+        COMMUTATOR = ===
+);
+CREATE OPERATOR !== (
+        PROCEDURE = int8ne,
+        LEFTARG = bigint,
+        RIGHTARG = bigint,
+        NEGATOR = ===,
+        COMMUTATOR = !==
+);
+DROP OPERATOR !==(bigint, bigint);
+SELECT  ctid, oprcom
+FROM    pg_catalog.pg_operator fk
+WHERE   oprcom != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprcom);
+ ctid | oprcom 
+------+--------
+(0 rows)
+
+SELECT  ctid, oprnegate
+FROM    pg_catalog.pg_operator fk
+WHERE   oprnegate != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprnegate);
+ ctid | oprnegate 
+------+-----------
+(0 rows)
+
+DROP OPERATOR ===(bigint, bigint);
+CREATE OPERATOR <| (
+        PROCEDURE = int8lt,
+        LEFTARG = bigint,
+        RIGHTARG = bigint
+);
+CREATE OPERATOR |> (
+        PROCEDURE = int8gt,
+        LEFTARG = bigint,
+        RIGHTARG = bigint,
+        NEGATOR = <|,
+        COMMUTATOR = <|
+);
+DROP OPERATOR |>(bigint, bigint);
+SELECT  ctid, oprcom
+FROM    pg_catalog.pg_operator fk
+WHERE   oprcom != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprcom);
+ ctid | oprcom 
+------+--------
+(0 rows)
+
+SELECT  ctid, oprnegate
+FROM    pg_catalog.pg_operator fk
+WHERE   oprnegate != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprnegate);
+ ctid | oprnegate 
+------+-----------
+(0 rows)
+
+DROP OPERATOR <|(bigint, bigint);

src/test/regress/parallel_schedule

@@ -84,7 +84,7 @@ test: select_into select_distinct select_distinct_on select_implicit select_havi
 # ----------
 # Another group of parallel tests
 # ----------
-test: brin gin gist spgist privileges security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets
+test: brin gin gist spgist privileges security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator
 
 # ----------
 # Another group of parallel tests

src/test/regress/serial_schedule

@@ -89,7 +89,6 @@ test: union
 test: case
 test: join
 test: aggregates
-test: groupingsets
 test: transactions
 ignore: random
 test: random
@@ -114,6 +113,8 @@ test: replica_identity
 test: rowsecurity
 test: object_address
 test: tablesample
+test: groupingsets
+test: drop_operator
 test: alter_generic
 test: alter_operator
 test: misc

src/test/regress/sql/drop_operator.sql

@@ -0,0 +1,56 @@
+CREATE OPERATOR === (
+        PROCEDURE = int8eq,
+        LEFTARG = bigint,
+        RIGHTARG = bigint,
+        COMMUTATOR = ===
+);
+
+CREATE OPERATOR !== (
+        PROCEDURE = int8ne,
+        LEFTARG = bigint,
+        RIGHTARG = bigint,
+        NEGATOR = ===,
+        COMMUTATOR = !==
+);
+
+DROP OPERATOR !==(bigint, bigint);
+
+SELECT  ctid, oprcom
+FROM    pg_catalog.pg_operator fk
+WHERE   oprcom != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprcom);
+
+SELECT  ctid, oprnegate
+FROM    pg_catalog.pg_operator fk
+WHERE   oprnegate != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprnegate);
+
+DROP OPERATOR ===(bigint, bigint);
+
+CREATE OPERATOR <| (
+        PROCEDURE = int8lt,
+        LEFTARG = bigint,
+        RIGHTARG = bigint
+);
+
+CREATE OPERATOR |> (
+        PROCEDURE = int8gt,
+        LEFTARG = bigint,
+        RIGHTARG = bigint,
+        NEGATOR = <|,
+        COMMUTATOR = <|
+);
+
+DROP OPERATOR |>(bigint, bigint);
+
+SELECT  ctid, oprcom
+FROM    pg_catalog.pg_operator fk
+WHERE   oprcom != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprcom);
+
+SELECT  ctid, oprnegate
+FROM    pg_catalog.pg_operator fk
+WHERE   oprnegate != 0 AND
+        NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator pk WHERE pk.oid = fk.oprnegate);
+
+DROP OPERATOR <|(bigint, bigint);