Support ALTER SYSTEM RESET command.

This patch allows us to execute ALTER SYSTEM RESET command to
remove the configuration entry from postgresql.auto.conf.

Vik Fearing, reviewed by Amit Kapila and me.

1 files changed, 31 insertions, 16 deletions

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 6f4d6455df6..b46dd7b008c 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -411,7 +411,8 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 %type <istmt>	insert_rest
 
-%type <vsetstmt> generic_set set_rest set_rest_more SetResetClause FunctionSetResetClause
+%type <vsetstmt> generic_set set_rest set_rest_more generic_reset reset_rest
+				 SetResetClause FunctionSetResetClause
 
 %type <node>	TableElement TypedTableElement ConstraintElem TableFuncElement
 %type <node>	columnDef columnOptions
@@ -1579,39 +1580,47 @@ NonReservedWord_or_Sconst:
 		;
 
 VariableResetStmt:
-			RESET var_name
+			RESET reset_rest						{ $$ = (Node *) $2; }
+		;
+
+reset_rest:
+			generic_reset							{ $$ = $1; }
+			| TIME ZONE
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
 					n->kind = VAR_RESET;
-					n->name = $2;
-					$$ = (Node *) n;
+					n->name = "timezone";
+					$$ = n;
 				}
-			| RESET TIME ZONE
+			| TRANSACTION ISOLATION LEVEL
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
 					n->kind = VAR_RESET;
-					n->name = "timezone";
-					$$ = (Node *) n;
+					n->name = "transaction_isolation";
+					$$ = n;
 				}
-			| RESET TRANSACTION ISOLATION LEVEL
+			| SESSION AUTHORIZATION
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
 					n->kind = VAR_RESET;
-					n->name = "transaction_isolation";
-					$$ = (Node *) n;
+					n->name = "session_authorization";
+					$$ = n;
 				}
-			| RESET SESSION AUTHORIZATION
+		;
+
+generic_reset:
+			var_name
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
 					n->kind = VAR_RESET;
-					n->name = "session_authorization";
-					$$ = (Node *) n;
+					n->name = $1;
+					$$ = n;
 				}
-			| RESET ALL
+			| ALL
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
 					n->kind = VAR_RESET_ALL;
-					$$ = (Node *) n;
+					$$ = n;
 				}
 		;
 
@@ -8494,7 +8503,7 @@ DropdbStmt: DROP DATABASE database_name
 
 /*****************************************************************************
  *
- *		ALTER SYSTEM SET
+ *		ALTER SYSTEM
  *
  * This is used to change configuration parameters persistently.
  *****************************************************************************/
@@ -8506,6 +8515,12 @@ AlterSystemStmt:
 					n->setstmt = $4;
 					$$ = (Node *)n;
 				}
+			| ALTER SYSTEM_P RESET generic_reset
+				{
+					AlterSystemStmt *n = makeNode(AlterSystemStmt);
+					n->setstmt = $4;
+					$$ = (Node *)n;
+				}
 		;