Remove the NODROP SLOT option from DROP SUBSCRIPTION

It turned out this approach had problems, because a DROP command should
not have any options other than CASCADE and RESTRICT.  Instead, always
attempt to drop the slot if there is one configured, but also add an
ALTER SUBSCRIPTION action to set the slot to NONE.

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/29431.1493730652@sss.pgh.pa.us

doc/src/sgml/ref/create_subscription.sgml

@@ -133,6 +133,15 @@ CREATE SUBSCRIPTION <replaceable class="PARAMETER">subscription_name</replaceabl
       Name of the replication slot to use. The default behavior is to use
       <literal>subscription_name</> for slot name.
      </para>
+
+     <para>
+      When <literal>SLOT NAME</literal> is set to
+      <literal>NONE</literal>, there will be no replication slot associated
+      with the subscription.  This can be used if the replication slot will be
+      created later manually.  Such subscriptions must also have both
+      <literal>ENABLED</literal> and <literal>CREATE SLOT</literal> set
+      to <literal>false</literal>.
+     </para>
     </listitem>
    </varlistentry>
 

doc/src/sgml/ref/drop_subscription.sgml

@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-DROP SUBSCRIPTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ DROP SLOT | NODROP SLOT ]
+DROP SUBSCRIPTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ CASCADE | RESTRICT ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -39,7 +39,9 @@ DROP SUBSCRIPTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable
 
   <para>
    <command>DROP SUBSCRIPTION</command> cannot be executed inside a
-   transaction block when <literal>DROP SLOT</literal> is specified.
+   transaction block if the subscription is associated with a replication
+   slot.  (You can use <command>ALTER SUBSCRIPTION</command> to unset the
+   slot.)
   </para>
  </refsect1>
 
@@ -57,20 +59,13 @@ DROP SUBSCRIPTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable
    </varlistentry>
 
    <varlistentry>
-    <term><literal>DROP SLOT</literal></term>
-    <term><literal>NODROP SLOT</literal></term>
-    <listitem>
-     <para>
-      Specifies whether to drop the replication slot on the publisher.  The
-      default is
-      <literal>DROP SLOT</literal>.
-     </para>
+    <term><literal>CASCADE</literal></term>
+    <term><literal>RESTRICT</literal></term>
 
+    <listitem>
      <para>
-      If the publisher is not reachable when the subscription is to be
-      dropped, then it is useful to specify <literal>NODROP SLOT</literal>.
-      But the replication slot on the publisher will then have to be removed
-      manually.
+      These key words do not have any effect, since there are no dependencies
+      on subscriptions.
      </para>
     </listitem>
    </varlistentry>

src/backend/catalog/pg_subscription.c

@@ -82,8 +82,10 @@ GetSubscription(Oid subid, bool missing_ok)
 							tup,
 							Anum_pg_subscription_subslotname,
 							&isnull);
-	Assert(!isnull);
-	sub->slotname = pstrdup(NameStr(*DatumGetName(datum)));
+	if (!isnull)
+		sub->slotname = pstrdup(NameStr(*DatumGetName(datum)));
+	else
+		sub->slotname = NULL;
 
 	/* Get synccommit */
 	datum = SysCacheGetAttr(SUBSCRIPTIONOID,
@@ -147,7 +149,8 @@ FreeSubscription(Subscription *sub)
 {
 	pfree(sub->name);
 	pfree(sub->conninfo);
-	pfree(sub->slotname);
+	if (sub->slotname)
+		pfree(sub->slotname);
 	list_free_deep(sub->publications);
 	pfree(sub);
 }

src/backend/commands/subscriptioncmds.c

@@ -60,7 +60,8 @@ static List *fetch_table_list(WalReceiverConn *wrconn, List *publications);
  */
 static void
 parse_subscription_options(List *options, bool *connect, bool *enabled_given,
-						   bool *enabled, bool *create_slot, char **slot_name,
+						   bool *enabled, bool *create_slot,
+						   bool *slot_name_given, char **slot_name,
 						   bool *copy_data, char **synchronous_commit)
 {
 	ListCell   *lc;
@@ -78,7 +79,10 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
 	if (create_slot)
 		*create_slot = true;
 	if (slot_name)
+	{
+		*slot_name_given = false;
 		*slot_name = NULL;
+	}
 	if (copy_data)
 		*copy_data = true;
 	if (synchronous_commit)
@@ -141,12 +145,17 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
 		}
 		else if (strcmp(defel->defname, "slot name") == 0 && slot_name)
 		{
-			if (*slot_name)
+			if (*slot_name_given)
 				ereport(ERROR,
 						(errcode(ERRCODE_SYNTAX_ERROR),
 						 errmsg("conflicting or redundant options")));
 
+			*slot_name_given = true;
 			*slot_name = defGetString(defel);
+
+			/* Setting slot_name = NONE is treated as no slot name. */
+			if (strcmp(*slot_name, "none") == 0)
+				*slot_name = NULL;
 		}
 		else if (strcmp(defel->defname, "copy data") == 0 && copy_data)
 		{
@@ -194,17 +203,17 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
 	if (connect && !*connect)
 	{
 		/* Check for incompatible options from the user. */
-		if (*enabled_given && *enabled)
+		if (enabled && *enabled_given && *enabled)
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("noconnect and enabled are mutually exclusive options")));
 
-		if (create_slot_given && *create_slot)
+		if (create_slot && create_slot_given && *create_slot)
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("noconnect and create slot are mutually exclusive options")));
 
-		if (copy_data_given && *copy_data)
+		if (copy_data && copy_data_given && *copy_data)
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("noconnect and copy data are mutually exclusive options")));
@@ -214,6 +223,23 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
 		*create_slot = false;
 		*copy_data = false;
 	}
+
+	/*
+	 * Do additional checking for disallowed combination when
+	 * slot_name = NONE was used.
+	 */
+	if (slot_name && *slot_name_given && !*slot_name)
+	{
+		if (enabled && *enabled_given && *enabled)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("slot_name = NONE and enabled are mutually exclusive options")));
+
+		if (create_slot && create_slot_given && *create_slot)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("slot_name = NONE and create slot are mutually exclusive options")));
+	}
 }
 
 /*
@@ -290,6 +316,7 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
 	char	   *synchronous_commit;
 	char	   *conninfo;
 	char	   *slotname;
+	bool		slotname_given;
 	char		originname[NAMEDATALEN];
 	bool		create_slot;
 	List	   *publications;
@@ -299,8 +326,8 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
 	 * Connection and publication should not be specified here.
 	 */
 	parse_subscription_options(stmt->options, &connect, &enabled_given,
-							   &enabled, &create_slot, &slotname, &copy_data,
-							   &synchronous_commit);
+							   &enabled, &create_slot, &slotname_given,
+							   &slotname, &copy_data, &synchronous_commit);
 
 	/*
 	 * Since creating a replication slot is not transactional, rolling back
@@ -329,8 +356,9 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
 						stmt->subname)));
 	}
 
-	if (slotname == NULL)
+	if (!slotname_given && slotname == NULL)
 		slotname = stmt->subname;
+
 	/* The default for synchronous_commit of subscriptions is off. */
 	if (synchronous_commit == NULL)
 		synchronous_commit = "off";
@@ -355,8 +383,11 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
 	values[Anum_pg_subscription_subenabled - 1] = BoolGetDatum(enabled);
 	values[Anum_pg_subscription_subconninfo - 1] =
 		CStringGetTextDatum(conninfo);
-	values[Anum_pg_subscription_subslotname - 1] =
-		DirectFunctionCall1(namein, CStringGetDatum(slotname));
+	if (slotname)
+		values[Anum_pg_subscription_subslotname - 1] =
+			DirectFunctionCall1(namein, CStringGetDatum(slotname));
+	else
+		nulls[Anum_pg_subscription_subslotname - 1] = true;
 	values[Anum_pg_subscription_subsynccommit - 1] =
 		CStringGetTextDatum(synchronous_commit);
 	values[Anum_pg_subscription_subpublications - 1] =
@@ -426,6 +457,8 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
 			 */
 			if (create_slot)
 			{
+				Assert(slotname);
+
 				walrcv_create_slot(wrconn, slotname, false,
 								   CRS_NOEXPORT_SNAPSHOT, &lsn);
 				ereport(NOTICE,
@@ -578,6 +611,7 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 	HeapTuple	tup;
 	Oid			subid;
 	bool		update_tuple = false;
+	Subscription   *sub;
 
 	rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
 
@@ -597,6 +631,7 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 					   stmt->subname);
 
 	subid = HeapTupleGetOid(tup);
+	sub = GetSubscription(subid, false);
 
 	/* Form a new tuple. */
 	memset(values, 0, sizeof(values));
@@ -607,19 +642,29 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 	{
 		case ALTER_SUBSCRIPTION_OPTIONS:
 			{
-				char *slot_name;
+				char	   *slotname;
+				bool		slotname_given;
 				char	   *synchronous_commit;
 
 				parse_subscription_options(stmt->options, NULL, NULL, NULL,
-										   NULL, &slot_name, NULL,
-										   &synchronous_commit);
+										   NULL, &slotname_given, &slotname,
+										   NULL, &synchronous_commit);
 
-				if (slot_name)
+				if (slotname_given)
 				{
-					values[Anum_pg_subscription_subslotname - 1] =
-						DirectFunctionCall1(namein, CStringGetDatum(slot_name));
+					if (sub->enabled && !slotname)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("cannot set slot_name = NONE for enabled subscription")));
+
+					if (slotname)
+						values[Anum_pg_subscription_subslotname - 1] =
+						DirectFunctionCall1(namein, CStringGetDatum(slotname));
+					else
+						nulls[Anum_pg_subscription_subslotname - 1] = true;
 					replaces[Anum_pg_subscription_subslotname - 1] = true;
 				}
+
 				if (synchronous_commit)
 				{
 					values[Anum_pg_subscription_subsynccommit - 1] =
@@ -638,9 +683,14 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 
 				parse_subscription_options(stmt->options, NULL,
 										   &enabled_given, &enabled, NULL,
-										   NULL, NULL, NULL);
+										   NULL, NULL, NULL, NULL);
 				Assert(enabled_given);
 
+				if (!sub->slotname && enabled)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("cannot enable subscription that does not have a slot name")));
+
 				values[Anum_pg_subscription_subenabled - 1] =
 					BoolGetDatum(enabled);
 				replaces[Anum_pg_subscription_subenabled - 1] = true;
@@ -668,10 +718,10 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 		case ALTER_SUBSCRIPTION_PUBLICATION_REFRESH:
 			{
 				bool			copy_data;
-				Subscription   *sub = GetSubscription(subid, false);
 
 				parse_subscription_options(stmt->options, NULL, NULL, NULL,
-										   NULL, NULL, &copy_data, NULL);
+										   NULL, NULL, NULL, &copy_data,
+										   NULL);
 
 				values[Anum_pg_subscription_subpublications - 1] =
 					 publicationListToArray(stmt->publication);
@@ -682,6 +732,11 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 				/* Refresh if user asked us to. */
 				if (stmt->kind == ALTER_SUBSCRIPTION_PUBLICATION_REFRESH)
 				{
+					if (!sub->enabled)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("ALTER SUBSCRIPTION ... REFRESH is not allowed for disabled subscriptions")));
+
 					/* Make sure refresh sees the new list of publications. */
 					sub->publications = stmt->publication;
 
@@ -694,10 +749,15 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 		case ALTER_SUBSCRIPTION_REFRESH:
 			{
 				bool			copy_data;
-				Subscription   *sub = GetSubscription(subid, false);
+
+				if (!sub->enabled)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("ALTER SUBSCRIPTION ... REFRESH is not allowed for disabled subscriptions")));
 
 				parse_subscription_options(stmt->options, NULL, NULL, NULL,
-										   NULL, NULL, &copy_data, NULL);
+										   NULL, NULL, NULL, &copy_data,
+										   NULL);
 
 				AlterSubscription_refresh(sub, copy_data);
 
@@ -750,15 +810,6 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	WalReceiverConn	   *wrconn = NULL;
 	StringInfoData		cmd;
 
-	/*
-	 * Since dropping a replication slot is not transactional, the replication
-	 * slot stays dropped even if the transaction rolls back.  So we cannot
-	 * run DROP SUBSCRIPTION inside a transaction block if dropping the
-	 * replication slot.
-	 */
-	if (stmt->drop_slot)
-		PreventTransactionChain(isTopLevel, "DROP SUBSCRIPTION ... DROP SLOT");
-
 	/*
 	 * Lock pg_subscription with AccessExclusiveLock to ensure
 	 * that the launcher doesn't restart new worker during dropping
@@ -817,8 +868,24 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	/* Get slotname */
 	datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
 							Anum_pg_subscription_subslotname, &isnull);
-	Assert(!isnull);
-	slotname = pstrdup(NameStr(*DatumGetName(datum)));
+	if (!isnull)
+		slotname = pstrdup(NameStr(*DatumGetName(datum)));
+	else
+		slotname = NULL;
+
+	/*
+	 * Since dropping a replication slot is not transactional, the replication
+	 * slot stays dropped even if the transaction rolls back.  So we cannot
+	 * run DROP SUBSCRIPTION inside a transaction block if dropping the
+	 * replication slot.
+	 *
+	 * XXX The command name should really be something like "DROP SUBSCRIPTION
+	 * of a subscription that is associated with a replication slot", but we
+	 * don't have the proper facilities for that.
+	 */
+	if (slotname)
+		PreventTransactionChain(isTopLevel, "DROP SUBSCRIPTION");
+
 
 	ObjectAddressSet(myself, SubscriptionRelationId, subid);
 	EventTriggerSQLDropAddObject(&myself, true, true);
@@ -843,8 +910,8 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	if (originid != InvalidRepOriginId)
 		replorigin_drop(originid);
 
-	/* If the user asked to not drop the slot, we are done mow.*/
-	if (!stmt->drop_slot)
+	/* If there is no slot associated with the subscription, we can finish here. */
+	if (!slotname)
 	{
 		heap_close(rel, NoLock);
 		return;
@@ -857,14 +924,16 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
 	load_file("libpqwalreceiver", false);
 
 	initStringInfo(&cmd);
-	appendStringInfo(&cmd, "DROP_REPLICATION_SLOT \"%s\"", slotname);
+	appendStringInfo(&cmd, "DROP_REPLICATION_SLOT %s", quote_identifier(slotname));
 
 	wrconn = walrcv_connect(conninfo, true, subname, &err);
 	if (wrconn == NULL)
 		ereport(ERROR,
 				(errmsg("could not connect to publisher when attempting to "
 						"drop the replication slot \"%s\"", slotname),
-				 errdetail("The error was: %s", err)));
+				 errdetail("The error was: %s", err),
+				 errhint("Use ALTER SUBSCRIPTION ... WITH (slot_name = NONE) "
+						 "to disassociate the subscription from the slot.")));
 
 	PG_TRY();
 	{

src/backend/nodes/copyfuncs.c

@@ -4537,8 +4537,8 @@ _copyDropSubscriptionStmt(const DropSubscriptionStmt *from)
 	DropSubscriptionStmt *newnode = makeNode(DropSubscriptionStmt);
 
 	COPY_STRING_FIELD(subname);
-	COPY_SCALAR_FIELD(drop_slot);
 	COPY_SCALAR_FIELD(missing_ok);
+	COPY_SCALAR_FIELD(behavior);
 
 	return newnode;
 }

src/backend/nodes/equalfuncs.c

@@ -2246,8 +2246,8 @@ _equalDropSubscriptionStmt(const DropSubscriptionStmt *a,
 						   const DropSubscriptionStmt *b)
 {
 	COMPARE_STRING_FIELD(subname);
-	COMPARE_SCALAR_FIELD(drop_slot);
 	COMPARE_SCALAR_FIELD(missing_ok);
+	COMPARE_SCALAR_FIELD(behavior);
 
 	return true;
 }

src/backend/parser/gram.y

@@ -415,7 +415,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <fun_param_mode> arg_class
 %type <typnam>	func_return func_type
 
-%type <boolean>  opt_trusted opt_restart_seqs opt_drop_slot
+%type <boolean>  opt_trusted opt_restart_seqs
 %type <ival>	 OptTemp
 %type <ival>	 OptNoLog
 %type <oncommit> OnCommitOption
@@ -467,7 +467,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <node>	def_arg columnElem where_clause where_or_current_clause
 				a_expr b_expr c_expr AexprConst indirection_el opt_slice_bound
 				columnref in_expr having_clause func_table xmltable array_expr
-				ExclusionWhereClause
+				ExclusionWhereClause operator_def_arg
 %type <list>	rowsfrom_item rowsfrom_list opt_col_def_list
 %type <boolean> opt_ordinality
 %type <list>	ExclusionConstraintList ExclusionConstraintElem
@@ -671,7 +671,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 	SAVEPOINT SCHEMA SCHEMAS SCROLL SEARCH SECOND_P SECURITY SELECT SEQUENCE SEQUENCES
 	SERIALIZABLE SERVER SESSION SESSION_USER SET SETS SETOF SHARE SHOW
-	SIMILAR SIMPLE SKIP SLOT SMALLINT SNAPSHOT SOME SQL_P STABLE STANDALONE_P
+	SIMILAR SIMPLE SKIP SMALLINT SNAPSHOT SOME SQL_P STABLE STANDALONE_P
 	START STATEMENT STATISTICS STDIN STDOUT STORAGE STRICT_P STRIP_P
 	SUBSCRIPTION SUBSTRING SYMMETRIC SYSID SYSTEM_P
 
@@ -5694,6 +5694,7 @@ def_arg:	func_type						{ $$ = (Node *)$1; }
 			| qual_all_Op					{ $$ = (Node *)$1; }
 			| NumericOnly					{ $$ = (Node *)$1; }
 			| Sconst						{ $$ = (Node *)makeString($1); }
+			| NONE							{ $$ = (Node *)makeString(pstrdup($1)); }
 		;
 
 old_aggr_definition: '(' old_aggr_list ')'			{ $$ = $2; }
@@ -8933,8 +8934,17 @@ operator_def_list:	operator_def_elem								{ $$ = list_make1($1); }
 
 operator_def_elem: ColLabel '=' NONE
 						{ $$ = makeDefElem($1, NULL, @1); }
-				   | ColLabel '=' def_arg
-					   { $$ = makeDefElem($1, (Node *) $3, @1); }
+				   | ColLabel '=' operator_def_arg
+						{ $$ = makeDefElem($1, (Node *) $3, @1); }
+		;
+
+/* must be similar enough to def_arg to avoid reduce/reduce conflicts */
+operator_def_arg:
+			func_type						{ $$ = (Node *)$1; }
+			| reserved_keyword				{ $$ = (Node *)makeString(pstrdup($1)); }
+			| qual_all_Op					{ $$ = (Node *)$1; }
+			| NumericOnly					{ $$ = (Node *)$1; }
+			| Sconst						{ $$ = (Node *)makeString($1); }
 		;
 
 /*****************************************************************************
@@ -9324,42 +9334,24 @@ AlterSubscriptionStmt:
  *
  *****************************************************************************/
 
-DropSubscriptionStmt: DROP SUBSCRIPTION name opt_drop_slot
+DropSubscriptionStmt: DROP SUBSCRIPTION name opt_drop_behavior
 				{
 					DropSubscriptionStmt *n = makeNode(DropSubscriptionStmt);
 					n->subname = $3;
-					n->drop_slot = $4;
 					n->missing_ok = false;
+					n->behavior = $4;
 					$$ = (Node *) n;
 				}
-				|  DROP SUBSCRIPTION IF_P EXISTS name opt_drop_slot
+				|  DROP SUBSCRIPTION IF_P EXISTS name opt_drop_behavior
 				{
 					DropSubscriptionStmt *n = makeNode(DropSubscriptionStmt);
 					n->subname = $5;
-					n->drop_slot = $6;
 					n->missing_ok = true;
+					n->behavior = $6;
 					$$ = (Node *) n;
 				}
 		;
 
-opt_drop_slot:
-			DROP SLOT
-				{
-					$$ = TRUE;
-				}
-			| IDENT SLOT
-				{
-					if (strcmp($1, "nodrop") == 0)
-						$$ = FALSE;
-					else
-						ereport(ERROR,
-								(errcode(ERRCODE_SYNTAX_ERROR),
-								 errmsg("unrecognized option \"%s\"", $1),
-										parser_errposition(@1)));
-				}
-			| /*EMPTY*/								{ $$ = TRUE; }
-		;
-
 /*****************************************************************************
  *
  *		QUERY:	Define Rewrite Rule
@@ -14846,7 +14838,6 @@ unreserved_keyword:
 			| SHOW
 			| SIMPLE
 			| SKIP
-			| SLOT
 			| SNAPSHOT
 			| SQL_P
 			| STABLE

src/backend/replication/logical/worker.c

@@ -1328,6 +1328,22 @@ reread_subscription(void)
 		proc_exit(0);
 	}
 
+	/*
+	 * Exit if the subscription was disabled.
+	 * This normally should not happen as the worker gets killed
+	 * during ALTER SUBSCRIPTION ... DISABLE.
+	 */
+	if (!newsub->enabled)
+	{
+		ereport(LOG,
+				(errmsg("logical replication worker for subscription \"%s\" will "
+						"stop because the subscription was disabled",
+						MySubscription->name)));
+
+		walrcv_disconnect(wrconn);
+		proc_exit(0);
+	}
+
 	/*
 	 * Exit if connection string was changed. The launcher will start
 	 * new worker.
@@ -1358,6 +1374,9 @@ reread_subscription(void)
 		proc_exit(0);
 	}
 
+	/* !slotname should never happen when enabled is true. */
+	Assert(newsub->slotname);
+
 	/*
 	 * We need to make new connection to new slot if slot name has changed
 	 * so exit here as well if that's the case.
@@ -1388,22 +1407,6 @@ reread_subscription(void)
 		proc_exit(0);
 	}
 
-	/*
-	 * Exit if the subscription was disabled.
-	 * This normally should not happen as the worker gets killed
-	 * during ALTER SUBSCRIPTION ... DISABLE.
-	 */
-	if (!newsub->enabled)
-	{
-		ereport(LOG,
-				(errmsg("logical replication worker for subscription \"%s\" will "
-						"stop because the subscription was disabled",
-						MySubscription->name)));
-
-		walrcv_disconnect(wrconn);
-		proc_exit(0);
-	}
-
 	/* Check for other changes that should never happen too. */
 	if (newsub->dbid != MySubscription->dbid)
 	{

src/bin/psql/tab-complete.c

@@ -2589,7 +2589,7 @@ psql_completion(const char *text, int start, int end)
 /* DROP */
 	/* Complete DROP object with CASCADE / RESTRICT */
 	else if (Matches3("DROP",
-					  "COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|TABLE|TYPE|VIEW",
+					  "COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|SUBSCRIPTION|TABLE|TYPE|VIEW",
 					  MatchAny) ||
 			 Matches4("DROP", "ACCESS", "METHOD", MatchAny) ||
 			 (Matches4("DROP", "AGGREGATE|FUNCTION", MatchAny, MatchAny) &&
@@ -2682,10 +2682,6 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches5("DROP", "RULE", MatchAny, "ON", MatchAny))
 		COMPLETE_WITH_LIST2("CASCADE", "RESTRICT");
 
-	/* DROP SUBSCRIPTION */
-	else if (Matches3("DROP", "SUBSCRIPTION", MatchAny))
-		COMPLETE_WITH_LIST2("DROP SLOT", "NODROP SLOT");
-
 /* EXECUTE */
 	else if (Matches1("EXECUTE"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_prepared_statements);

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201704211
+#define CATALOG_VERSION_NO	201705091
 
 #endif

src/include/catalog/pg_subscription.h

@@ -45,7 +45,7 @@ CATALOG(pg_subscription,6100) BKI_SHARED_RELATION BKI_ROWTYPE_OID(6101) BKI_SCHE
 	text		subconninfo BKI_FORCE_NOT_NULL;
 
 	/* Slot name on publisher */
-	NameData	subslotname BKI_FORCE_NOT_NULL;
+	NameData	subslotname;
 
 	/* Synchronous commit setting for worker */
 	text		subsynccommit BKI_FORCE_NOT_NULL;

src/include/nodes/parsenodes.h

@@ -3393,8 +3393,8 @@ typedef struct DropSubscriptionStmt
 {
 	NodeTag		type;
 	char	   *subname;		/* Name of of the subscription */
-	bool		drop_slot;		/* Should we drop the slot on remote side? */
 	bool		missing_ok;		/* Skip error if missing? */
+	DropBehavior behavior;		/* RESTRICT or CASCADE behavior */
 } DropSubscriptionStmt;
 
 #endif   /* PARSENODES_H */

src/include/parser/kwlist.h

@@ -366,7 +366,6 @@ PG_KEYWORD("show", SHOW, UNRESERVED_KEYWORD)
 PG_KEYWORD("similar", SIMILAR, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("simple", SIMPLE, UNRESERVED_KEYWORD)
 PG_KEYWORD("skip", SKIP, UNRESERVED_KEYWORD)
-PG_KEYWORD("slot", SLOT, UNRESERVED_KEYWORD)
 PG_KEYWORD("smallint", SMALLINT, COL_NAME_KEYWORD)
 PG_KEYWORD("snapshot", SNAPSHOT, UNRESERVED_KEYWORD)
 PG_KEYWORD("some", SOME, RESERVED_KEYWORD)

src/test/modules/dummy_seclabel/expected/dummy_seclabel.out

@@ -69,7 +69,7 @@ CREATE SCHEMA dummy_seclabel_test;
 SECURITY LABEL ON SCHEMA dummy_seclabel_test IS 'unclassified';		-- OK
 SET client_min_messages = error;
 CREATE PUBLICATION dummy_pub;
-CREATE SUBSCRIPTION dummy_sub CONNECTION '' PUBLICATION foo WITH (NOCONNECT);
+CREATE SUBSCRIPTION dummy_sub CONNECTION '' PUBLICATION foo WITH (NOCONNECT, SLOT NAME = NONE);
 RESET client_min_messages;
 SECURITY LABEL ON PUBLICATION dummy_pub IS 'classified';
 SECURITY LABEL ON SUBSCRIPTION dummy_sub IS 'classified';
@@ -111,7 +111,7 @@ NOTICE:  event ddl_command_end: SECURITY LABEL
 DROP EVENT TRIGGER always_start, always_end, always_drop, always_rewrite;
 DROP VIEW dummy_seclabel_view1;
 DROP TABLE dummy_seclabel_tbl1, dummy_seclabel_tbl2;
-DROP SUBSCRIPTION dummy_sub NODROP SLOT;
+DROP SUBSCRIPTION dummy_sub;
 DROP PUBLICATION dummy_pub;
 DROP ROLE regress_dummy_seclabel_user1;
 DROP ROLE regress_dummy_seclabel_user2;

src/test/modules/dummy_seclabel/sql/dummy_seclabel.sql

@@ -73,7 +73,7 @@ SECURITY LABEL ON SCHEMA dummy_seclabel_test IS 'unclassified';		-- OK
 
 SET client_min_messages = error;
 CREATE PUBLICATION dummy_pub;
-CREATE SUBSCRIPTION dummy_sub CONNECTION '' PUBLICATION foo WITH (NOCONNECT);
+CREATE SUBSCRIPTION dummy_sub CONNECTION '' PUBLICATION foo WITH (NOCONNECT, SLOT NAME = NONE);
 RESET client_min_messages;
 SECURITY LABEL ON PUBLICATION dummy_pub IS 'classified';
 SECURITY LABEL ON SUBSCRIPTION dummy_sub IS 'classified';
@@ -108,7 +108,7 @@ DROP EVENT TRIGGER always_start, always_end, always_drop, always_rewrite;
 DROP VIEW dummy_seclabel_view1;
 DROP TABLE dummy_seclabel_tbl1, dummy_seclabel_tbl2;
 
-DROP SUBSCRIPTION dummy_sub NODROP SLOT;
+DROP SUBSCRIPTION dummy_sub;
 DROP PUBLICATION dummy_pub;
 
 DROP ROLE regress_dummy_seclabel_user1;

src/test/regress/expected/object_address.out

@@ -37,7 +37,7 @@ CREATE TRANSFORM FOR int LANGUAGE SQL (
 	FROM SQL WITH FUNCTION varchar_transform(internal),
 	TO SQL WITH FUNCTION int4recv(internal));
 CREATE PUBLICATION addr_pub FOR TABLE addr_nsp.gentable;
-CREATE SUBSCRIPTION addr_sub CONNECTION '' PUBLICATION bar WITH (DISABLED, NOCONNECT);
+CREATE SUBSCRIPTION addr_sub CONNECTION '' PUBLICATION bar WITH (NOCONNECT, SLOT NAME = NONE);
 WARNING:  tables were not subscribed, you will have to run ALTER SUBSCRIPTION ... REFRESH PUBLICATION to subscribe the tables
 CREATE STATISTICS addr_nsp.gentable_stat ON (a,b) FROM addr_nsp.gentable;
 -- test some error cases
@@ -477,7 +477,7 @@ SELECT (pg_identify_object(addr1.classid, addr1.objid, addr1.objsubid)).*,
 SET client_min_messages TO 'warning';
 DROP FOREIGN DATA WRAPPER addr_fdw CASCADE;
 DROP PUBLICATION addr_pub;
-DROP SUBSCRIPTION addr_sub NODROP SLOT;
+DROP SUBSCRIPTION addr_sub;
 DROP SCHEMA addr_nsp CASCADE;
 DROP OWNED BY regress_addr_user;
 DROP USER regress_addr_user;

src/test/regress/expected/subscription.out

@@ -113,17 +113,19 @@ HINT:  The owner of a subscription must be a superuser.
 ALTER ROLE regress_subscription_user2 SUPERUSER;
 -- now it works
 ALTER SUBSCRIPTION testsub OWNER TO regress_subscription_user2;
--- fail - cannot do DROP SUBSCRIPTION DROP SLOT inside transaction block
+-- fail - cannot do DROP SUBSCRIPTION inside transaction block with slot name
 BEGIN;
-DROP SUBSCRIPTION testsub DROP SLOT;
-ERROR:  DROP SUBSCRIPTION ... DROP SLOT cannot run inside a transaction block
+DROP SUBSCRIPTION testsub;
+ERROR:  DROP SUBSCRIPTION cannot run inside a transaction block
 COMMIT;
+ALTER SUBSCRIPTION testsub WITH (SLOT NAME = NONE);
+-- now it works
 BEGIN;
-DROP SUBSCRIPTION testsub NODROP SLOT;
+DROP SUBSCRIPTION testsub;
 COMMIT;
-DROP SUBSCRIPTION IF EXISTS testsub NODROP SLOT;
+DROP SUBSCRIPTION IF EXISTS testsub;
 NOTICE:  subscription "testsub" does not exist, skipping
-DROP SUBSCRIPTION testsub NODROP SLOT;  -- fail
+DROP SUBSCRIPTION testsub;  -- fail
 ERROR:  subscription "testsub" does not exist
 RESET SESSION AUTHORIZATION;
 DROP ROLE regress_subscription_user;

src/test/regress/sql/object_address.sql

@@ -40,7 +40,7 @@ CREATE TRANSFORM FOR int LANGUAGE SQL (
 	FROM SQL WITH FUNCTION varchar_transform(internal),
 	TO SQL WITH FUNCTION int4recv(internal));
 CREATE PUBLICATION addr_pub FOR TABLE addr_nsp.gentable;
-CREATE SUBSCRIPTION addr_sub CONNECTION '' PUBLICATION bar WITH (DISABLED, NOCONNECT);
+CREATE SUBSCRIPTION addr_sub CONNECTION '' PUBLICATION bar WITH (NOCONNECT, SLOT NAME = NONE);
 CREATE STATISTICS addr_nsp.gentable_stat ON (a,b) FROM addr_nsp.gentable;
 
 -- test some error cases
@@ -205,7 +205,7 @@ SET client_min_messages TO 'warning';
 
 DROP FOREIGN DATA WRAPPER addr_fdw CASCADE;
 DROP PUBLICATION addr_pub;
-DROP SUBSCRIPTION addr_sub NODROP SLOT;
+DROP SUBSCRIPTION addr_sub;
 
 DROP SCHEMA addr_nsp CASCADE;
 

src/test/regress/sql/subscription.sql

@@ -83,17 +83,20 @@ ALTER ROLE regress_subscription_user2 SUPERUSER;
 -- now it works
 ALTER SUBSCRIPTION testsub OWNER TO regress_subscription_user2;
 
--- fail - cannot do DROP SUBSCRIPTION DROP SLOT inside transaction block
+-- fail - cannot do DROP SUBSCRIPTION inside transaction block with slot name
 BEGIN;
-DROP SUBSCRIPTION testsub DROP SLOT;
+DROP SUBSCRIPTION testsub;
 COMMIT;
 
+ALTER SUBSCRIPTION testsub WITH (SLOT NAME = NONE);
+
+-- now it works
 BEGIN;
-DROP SUBSCRIPTION testsub NODROP SLOT;
+DROP SUBSCRIPTION testsub;
 COMMIT;
 
-DROP SUBSCRIPTION IF EXISTS testsub NODROP SLOT;
-DROP SUBSCRIPTION testsub NODROP SLOT;  -- fail
+DROP SUBSCRIPTION IF EXISTS testsub;
+DROP SUBSCRIPTION testsub;  -- fail
 
 RESET SESSION AUTHORIZATION;
 DROP ROLE regress_subscription_user;

src/test/subscription/t/001_rep_changes.pl

@@ -191,7 +191,7 @@ $node_publisher->poll_query_until('postgres',
   or die "Timed out while waiting for apply to restart";
 
 # check all the cleanup
-$node_subscriber->safe_psql('postgres', "DROP SUBSCRIPTION tap_sub_renamed DROP SLOT");
+$node_subscriber->safe_psql('postgres', "DROP SUBSCRIPTION tap_sub_renamed");
 
 $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM pg_subscription");