Corrections to replication slots code and documentation.

Andres Freund, per a report from Vik Faering

doc/src/sgml/func.sgml

@@ -16317,10 +16317,10 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
         <indexterm>
          <primary>pg_create_physical_replication_slot</primary>
         </indexterm>
-        <literal><function>pg_create_physical_replication_slot(<parameter>slotname</parameter> <type>text</type>, <parameter>plugin</parameter> <type>text</type>)</function></literal>
+        <literal><function>pg_create_physical_replication_slot(<parameter>slotname</parameter> <type>name</type>)</function></literal>
        </entry>
        <entry>
-        (<parameter>slotname</parameter> <type>text</type>, <parameter>xlog_position</parameter> <type>pg_lsn</type>)
+        (<parameter>slotname</parameter> <type>name</type>, <parameter>xlog_position</parameter> <type>pg_lsn</type>)
        </entry>
        <entry>
         Creates a new physical replication slot named
@@ -16335,10 +16335,10 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
         <indexterm>
          <primary>pg_drop_replication_slot</primary>
         </indexterm>
-        <literal><function>pg_drop_replication_slot(<parameter>slotname</parameter> <type>text</type>)</function></literal>
+        <literal><function>pg_drop_replication_slot(<parameter>slotname</parameter> <type>name</type>)</function></literal>
        </entry>
        <entry>
-        (<parameter>slotname</parameter> <type>text</type>)
+        <type>void</type>
        </entry>
        <entry>
         Drops the physical or logical replication slot

doc/src/sgml/high-availability.sgml

@@ -935,7 +935,7 @@ postgres=# SELECT * FROM pg_create_physical_replication_slot('node_a_slot');
 postgres=# SELECT * FROM pg_replication_slots;
   slot_name  | slot_type | datoid | database | active | xmin | restart_lsn
 -------------+-----------+--------+----------+--------+------+-------------
- node_a_slot | physical  |      0 |          | f      |      |
+ node_a_slot | physical  |        |          | f      |      |
 (1 row)
 </programlisting>
      To configure the standby to use this slot, <varname>primary_slotname</>

src/backend/replication/slotfuncs.c

@@ -56,7 +56,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
 	/* acquire replication slot, this will check for conflicting names*/
 	ReplicationSlotCreate(NameStr(*name), false);
 
-	values[0] = CStringGetTextDatum(NameStr(MyReplicationSlot->data.name));
+	values[0] = NameGetDatum(&MyReplicationSlot->data.name);
 
 	nulls[0] = false;
 	nulls[1] = true;
@@ -141,7 +141,8 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
 		XLogRecPtr	restart_lsn;
 		bool		active;
 		Oid			database;
-		const char *slot_name;
+		NameData	slot_name;
+
 		int			i;
 
 		SpinLockAcquire(&slot->mutex);
@@ -155,7 +156,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
 			xmin = slot->data.xmin;
 			database = slot->data.database;
 			restart_lsn = slot->data.restart_lsn;
-			slot_name = pstrdup(NameStr(slot->data.name));
+			namecpy(&slot_name, &slot->data.name);
 
 			active = slot->active;
 		}
@@ -164,11 +165,14 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
 		memset(nulls, 0, sizeof(nulls));
 
 		i = 0;
-		values[i++] = CStringGetTextDatum(slot_name);
+		values[i++] = NameGetDatum(&slot_name);
 		if (database == InvalidOid)
 			values[i++] = CStringGetTextDatum("physical");
 		else
 			values[i++] = CStringGetTextDatum("logical");
+		if (database == InvalidOid)
+			nulls[i++] = true;
+		else
 			values[i++] = database;
 		values[i++] = BoolGetDatum(active);
 		if (xmin != InvalidTransactionId)

src/include/catalog/pg_proc.h

@@ -4800,11 +4800,11 @@ DATA(insert OID = 3473 (  spg_range_quad_leaf_consistent	PGNSP PGUID 12 1 0 0 0
 DESCR("SP-GiST support for quad tree over range");
 
 /* replication slots */
-DATA(insert OID = 3779 (  pg_create_physical_replication_slot PGNSP PGUID 12 1 0 0 0 f f f f f f v 1 0 2249 "19" "{19,25,3220}" "{i,o,o}" "{slotname,slotname,xlog_position}" _null_ pg_create_physical_replication_slot _null_ _null_ _null_ ));
+DATA(insert OID = 3779 (  pg_create_physical_replication_slot PGNSP PGUID 12 1 0 0 0 f f f f f f v 1 0 2249 "19" "{19,19,3220}" "{i,o,o}" "{slotname,slotname,xlog_position}" _null_ pg_create_physical_replication_slot _null_ _null_ _null_ ));
 DESCR("create a physical replication slot");
 DATA(insert OID = 3780 (  pg_drop_replication_slot PGNSP PGUID 12 1 0 0 0 f f f f f f v 1 0 2278 "19" _null_ _null_ _null_ _null_ pg_drop_replication_slot _null_ _null_ _null_ ));
 DESCR("drop a replication slot");
-DATA(insert OID = 3781 (  pg_get_replication_slots	PGNSP PGUID 12 1 10 0 0 f f f f f t s 0 0 2249 "" "{25,25,26,16,28,3220}" "{o,o,o,o,o,o}" "{slot_name,slot_type,datoid,active,xmin,restart_lsn}" _null_ pg_get_replication_slots _null_ _null_ _null_ ));
+DATA(insert OID = 3781 (  pg_get_replication_slots	PGNSP PGUID 12 1 10 0 0 f f f f f t s 0 0 2249 "" "{19,25,26,16,28,3220}" "{o,o,o,o,o,o}" "{slot_name,slot_type,datoid,active,xmin,restart_lsn}" _null_ pg_get_replication_slots _null_ _null_ _null_ ));
 DESCR("information about replication slots currently in use");
 
 /* event triggers */