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.

1 files changed, 31 insertions, 3 deletions

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index e0ff6f16a21..2b02a2e5233 100644
--- a/src/backend/parser/gram.y
+++ b/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
@@ -8198,6 +8199,33 @@ 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
  *
  *****************************************************************************/