Add ALTER OPERATOR command, for changing selectivity estimator functions.

Other options cannot be changed, as it's not totally clear if cached plans
would need to be invalidated if one of the other options change. Selectivity
estimator functions only change plan costs, not correctness of plans, so
those should be safe.

Original patch by Uriy Zhuravlev, heavily edited by me.

doc/src/sgml/ref/alter_operator.sgml

@@ -26,6 +26,11 @@ ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</repla
 
 ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</replaceable> | NONE } , { <replaceable>right_type</replaceable> | NONE } )
     SET SCHEMA <replaceable>new_schema</replaceable>
+
+ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</replaceable> | NONE } , { <replaceable>right_type</replaceable> | NONE } )
+    SET ( {  RESTRICT = { <replaceable class="parameter">res_proc</replaceable> | NONE }
+           | JOIN = { <replaceable class="parameter">join_proc</replaceable> | NONE }
+         } [, ... ] )
 </synopsis>
  </refsynopsisdiv>
 
@@ -34,8 +39,7 @@ ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</repla
 
   <para>
    <command>ALTER OPERATOR</command> changes the definition of
-   an operator.  The only currently available functionality is to change the
-   owner of the operator.
+   an operator.
   </para>
 
   <para>
@@ -98,6 +102,25 @@ ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</repla
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+     <term><replaceable class="parameter">res_proc</replaceable></term>
+     <listitem>
+       <para>
+         The restriction selectivity estimator function for this operator; write NONE to remove existing selectivity estimator.
+       </para>
+      </listitem>
+   </varlistentry>
+
+   <varlistentry>
+     <term><replaceable class="parameter">join_proc</replaceable></term>
+     <listitem>
+       <para>
+         The join selectivity estimator function for this operator; write NONE to remove existing selectivity estimator.
+       </para>
+     </listitem>
+   </varlistentry>
+
   </variablelist>
  </refsect1>
 
@@ -109,6 +132,13 @@ ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</repla
 <programlisting>
 ALTER OPERATOR @@ (text, text) OWNER TO joe;
 </programlisting></para>
+
+  <para>
+    Change the restriction and join selectivity estimator functions of a custom operator <literal>a && b</literal> for type <type>int[]</type>:
+<programlisting>
+ALTER OPERATOR && (_int4, _int4) SET (RESTRICT = _int_contsel, JOIN = _int_contjoinsel);
+</programlisting></para>
+
  </refsect1>
 
  <refsect1>

src/backend/nodes/copyfuncs.c

@@ -3212,6 +3212,18 @@ _copyAlterOwnerStmt(const AlterOwnerStmt *from)
 	return newnode;
 }
 
+static AlterOperatorStmt *
+_copyAlterOperatorStmt(const AlterOperatorStmt *from)
+{
+	AlterOperatorStmt *newnode = makeNode(AlterOperatorStmt);
+
+	COPY_NODE_FIELD(opername);
+	COPY_NODE_FIELD(operargs);
+	COPY_NODE_FIELD(options);
+
+	return newnode;
+}
+
 static RuleStmt *
 _copyRuleStmt(const RuleStmt *from)
 {
@@ -4615,6 +4627,9 @@ copyObject(const void *from)
 		case T_AlterOwnerStmt:
 			retval = _copyAlterOwnerStmt(from);
 			break;
+		case T_AlterOperatorStmt:
+			retval = _copyAlterOperatorStmt(from);
+			break;
 		case T_RuleStmt:
 			retval = _copyRuleStmt(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -1338,6 +1338,16 @@ _equalAlterOwnerStmt(const AlterOwnerStmt *a, const AlterOwnerStmt *b)
 	return true;
 }
 
+static bool
+_equalAlterOperatorStmt(const AlterOperatorStmt *a, const AlterOperatorStmt *b)
+{
+	COMPARE_NODE_FIELD(opername);
+	COMPARE_NODE_FIELD(operargs);
+	COMPARE_NODE_FIELD(options);
+
+	return true;
+}
+
 static bool
 _equalRuleStmt(const RuleStmt *a, const RuleStmt *b)
 {
@@ -2980,6 +2990,9 @@ equal(const void *a, const void *b)
 		case T_AlterOwnerStmt:
 			retval = _equalAlterOwnerStmt(a, b);
 			break;
+		case T_AlterOperatorStmt:
+			retval = _equalAlterOperatorStmt(a, b);
+			break;
 		case T_RuleStmt:
 			retval = _equalRuleStmt(a, b);
 			break;

src/backend/parser/gram.y

@@ -232,7 +232,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 		AlterEventTrigStmt
 		AlterDatabaseStmt AlterDatabaseSetStmt AlterDomainStmt AlterEnumStmt
 		AlterFdwStmt AlterForeignServerStmt AlterGroupStmt
-		AlterObjectSchemaStmt AlterOwnerStmt AlterSeqStmt AlterSystemStmt AlterTableStmt
+		AlterObjectSchemaStmt AlterOwnerStmt AlterOperatorStmt AlterSeqStmt AlterSystemStmt AlterTableStmt
 		AlterTblSpcStmt AlterExtensionStmt AlterExtensionContentsStmt AlterForeignTableStmt
 		AlterCompositeTypeStmt AlterUserStmt AlterUserMappingStmt AlterUserSetStmt
 		AlterRoleStmt AlterRoleSetStmt AlterPolicyStmt
@@ -359,7 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				any_operator expr_list attrs
 				target_list opt_target_list insert_column_list set_target_list
 				set_clause_list set_clause multiple_set_clause
-				ctext_expr_list ctext_row def_list indirection opt_indirection
+				ctext_expr_list ctext_row def_list operator_def_list indirection opt_indirection
 				reloption_list group_clause TriggerFuncArgs select_limit
 				opt_select_limit opclass_item_list opclass_drop_list
 				opclass_purpose opt_opfamily transaction_mode_list_or_empty
@@ -432,7 +432,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 %type <node>	TableElement TypedTableElement ConstraintElem TableFuncElement
 %type <node>	columnDef columnOptions
-%type <defelt>	def_elem reloption_elem old_aggr_elem
+%type <defelt>	def_elem reloption_elem old_aggr_elem operator_def_elem
 %type <node>	def_arg columnElem where_clause where_or_current_clause
 				a_expr b_expr c_expr AexprConst indirection_el
 				columnref in_expr having_clause func_table array_expr
@@ -769,6 +769,7 @@ stmt :
 			| AlterGroupStmt
 			| AlterObjectSchemaStmt
 			| AlterOwnerStmt
+			| AlterOperatorStmt
 			| AlterPolicyStmt
 			| AlterSeqStmt
 			| AlterSystemStmt
@@ -8196,6 +8197,33 @@ AlterObjectSchemaStmt:
 				}
 		;
 
+/*****************************************************************************
+ *
+ * ALTER OPERATOR name SET define
+ *
+ *****************************************************************************/
+
+AlterOperatorStmt:
+			ALTER OPERATOR any_operator oper_argtypes SET '(' operator_def_list ')'
+				{
+					AlterOperatorStmt *n = makeNode(AlterOperatorStmt);
+					n->opername = $3;
+					n->operargs = $4;
+					n->options = $7;
+					$$ = (Node *)n;
+				}
+		;
+
+operator_def_list:	operator_def_elem								{ $$ = list_make1($1); }
+			| operator_def_list ',' operator_def_elem				{ $$ = lappend($1, $3); }
+		;
+
+operator_def_elem: ColLabel '=' NONE
+						{ $$ = makeDefElem($1, NULL); }
+				   | ColLabel '=' def_arg
+						{ $$ = makeDefElem($1, (Node *) $3); }
+		;
+
 /*****************************************************************************
  *
  * ALTER THING name OWNER TO newname

src/backend/tcop/utility.c

@@ -149,6 +149,7 @@ check_xact_readonly(Node *parsetree)
 		case T_AlterRoleSetStmt:
 		case T_AlterObjectSchemaStmt:
 		case T_AlterOwnerStmt:
+		case T_AlterOperatorStmt:
 		case T_AlterSeqStmt:
 		case T_AlterTableMoveAllStmt:
 		case T_AlterTableStmt:
@@ -1481,6 +1482,10 @@ ProcessUtilitySlow(Node *parsetree,
 				address = ExecAlterOwnerStmt((AlterOwnerStmt *) parsetree);
 				break;
 
+			case T_AlterOperatorStmt:
+				address = AlterOperator((AlterOperatorStmt *) parsetree);
+				break;
+
 			case T_CommentStmt:
 				address = CommentObject((CommentStmt *) parsetree);
 				break;
@@ -2494,6 +2499,10 @@ CreateCommandTag(Node *parsetree)
 			tag = "ALTER OPERATOR FAMILY";
 			break;
 
+		case T_AlterOperatorStmt:
+			tag = "ALTER OPERATOR";
+			break;
+
 		case T_AlterTSDictionaryStmt:
 			tag = "ALTER TEXT SEARCH DICTIONARY";
 			break;

src/include/commands/defrem.h

@@ -73,6 +73,7 @@ extern void interpret_function_parameter_list(List *parameters,
 /* commands/operatorcmds.c */
 extern ObjectAddress DefineOperator(List *names, List *parameters);
 extern void RemoveOperatorById(Oid operOid);
+extern ObjectAddress AlterOperator(AlterOperatorStmt *stmt);
 
 /* commands/aggregatecmds.c */
 extern ObjectAddress DefineAggregate(List *name, List *args, bool oldstyle,

src/include/nodes/nodes.h

@@ -347,6 +347,7 @@ typedef enum NodeTag
 	T_DropTableSpaceStmt,
 	T_AlterObjectSchemaStmt,
 	T_AlterOwnerStmt,
+	T_AlterOperatorStmt,
 	T_DropOwnedStmt,
 	T_ReassignOwnedStmt,
 	T_CompositeTypeStmt,

src/include/nodes/parsenodes.h

@@ -2543,6 +2543,19 @@ typedef struct AlterOwnerStmt
 } AlterOwnerStmt;
 
 
+/* ----------------------
+ *		Alter Operator Set Restrict, Join
+ * ----------------------
+ */
+typedef struct AlterOperatorStmt
+{
+	NodeTag		type;
+	List	   *opername;		/* operator name */
+	List	   *operargs;		/* operator's argument TypeNames */
+	List	   *options;		/* List of DefElem nodes */
+} AlterOperatorStmt;
+
+
 /* ----------------------
  *		Create Rule Statement
  * ----------------------

src/test/regress/expected/alter_operator.out

+CREATE OR REPLACE FUNCTION alter_op_test_fn(boolean, boolean)
+RETURNS boolean AS $$ SELECT NULL::BOOLEAN; $$ LANGUAGE sql IMMUTABLE;
+CREATE OPERATOR === (
+    LEFTARG = boolean,
+    RIGHTARG = boolean,
+    PROCEDURE = alter_op_test_fn,
+    COMMUTATOR = ===,
+    NEGATOR = !==,
+    RESTRICT = contsel,
+    JOIN = contjoinsel,
+    HASHES, MERGES
+);
+--
+-- Reset and set params
+--
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = NONE);
+ALTER OPERATOR === (boolean, boolean) SET (JOIN = NONE);
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+ oprrest | oprjoin 
+---------+---------
+ -       | -
+(1 row)
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = contsel);
+ALTER OPERATOR === (boolean, boolean) SET (JOIN = contjoinsel);
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+ oprrest |   oprjoin   
+---------+-------------
+ contsel | contjoinsel
+(1 row)
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = NONE, JOIN = NONE);
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+ oprrest | oprjoin 
+---------+---------
+ -       | -
+(1 row)
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = contsel, JOIN = contjoinsel);
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+ oprrest |   oprjoin   
+---------+-------------
+ contsel | contjoinsel
+(1 row)
+
+--
+-- Test invalid options.
+--
+ALTER OPERATOR === (boolean, boolean) SET (COMMUTATOR = ====);
+ERROR:  operator attribute "commutator" can not be changed
+ALTER OPERATOR === (boolean, boolean) SET (NEGATOR = ====);
+ERROR:  operator attribute "negator" can not be changed
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = non_existent_func);
+ERROR:  function non_existent_func(internal, oid, internal, integer) does not exist
+ALTER OPERATOR === (boolean, boolean) SET (JOIN = non_existent_func);
+ERROR:  function non_existent_func(internal, oid, internal, smallint, internal) does not exist
+ALTER OPERATOR === (boolean, boolean) SET (COMMUTATOR = !==);
+ERROR:  operator attribute "commutator" can not be changed
+ALTER OPERATOR === (boolean, boolean) SET (NEGATOR = !==);
+ERROR:  operator attribute "negator" can not be changed
+--
+-- Test permission check. Must be owner to ALTER OPERATOR.
+--
+CREATE USER regtest_alter_user;
+SET SESSION AUTHORIZATION regtest_alter_user_user;
+ERROR:  role "regtest_alter_user_user" does not exist
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = NONE);
+RESET SESSION AUTHORIZATION;
+-- Clean up
+DROP USER regression_alter_user;
+ERROR:  role "regression_alter_user" does not exist
+DROP OPERATOR === (boolean, boolean);

src/test/regress/parallel_schedule

@@ -89,7 +89,7 @@ test: brin gin gist spgist privileges security_label collate matview lock replic
 # ----------
 # Another group of parallel tests
 # ----------
-test: alter_generic misc psql async
+test: alter_generic alter_operator misc psql async
 
 # rules cannot run concurrently with any test that creates a view
 test: rules

src/test/regress/serial_schedule

@@ -111,6 +111,7 @@ test: replica_identity
 test: rowsecurity
 test: object_address
 test: alter_generic
+test: alter_operator
 test: misc
 test: psql
 test: async

src/test/regress/sql/alter_operator.sql

+CREATE OR REPLACE FUNCTION alter_op_test_fn(boolean, boolean)
+RETURNS boolean AS $$ SELECT NULL::BOOLEAN; $$ LANGUAGE sql IMMUTABLE;
+
+CREATE OPERATOR === (
+    LEFTARG = boolean,
+    RIGHTARG = boolean,
+    PROCEDURE = alter_op_test_fn,
+    COMMUTATOR = ===,
+    NEGATOR = !==,
+    RESTRICT = contsel,
+    JOIN = contjoinsel,
+    HASHES, MERGES
+);
+
+--
+-- Reset and set params
+--
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = NONE);
+ALTER OPERATOR === (boolean, boolean) SET (JOIN = NONE);
+
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = contsel);
+ALTER OPERATOR === (boolean, boolean) SET (JOIN = contjoinsel);
+
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = NONE, JOIN = NONE);
+
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = contsel, JOIN = contjoinsel);
+
+SELECT oprrest, oprjoin FROM pg_operator WHERE oprname = '==='
+  AND oprleft = 'boolean'::regtype AND oprright = 'boolean'::regtype;
+
+--
+-- Test invalid options.
+--
+ALTER OPERATOR === (boolean, boolean) SET (COMMUTATOR = ====);
+ALTER OPERATOR === (boolean, boolean) SET (NEGATOR = ====);
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = non_existent_func);
+ALTER OPERATOR === (boolean, boolean) SET (JOIN = non_existent_func);
+ALTER OPERATOR === (boolean, boolean) SET (COMMUTATOR = !==);
+ALTER OPERATOR === (boolean, boolean) SET (NEGATOR = !==);
+
+
+--
+-- Test permission check. Must be owner to ALTER OPERATOR.
+--
+CREATE USER regtest_alter_user;
+SET SESSION AUTHORIZATION regtest_alter_user_user;
+
+ALTER OPERATOR === (boolean, boolean) SET (RESTRICT = NONE);
+
+RESET SESSION AUTHORIZATION;
+
+-- Clean up
+DROP USER regression_alter_user;
+DROP OPERATOR === (boolean, boolean);