Don't check status of logical replication slots

We only want to check the status of physical replication slots
to determine whether a streaming replication standby has become
detached and there is therefore a risk of uncontrolled WAL buildup
on the local node.

It's not feasible to second-guess the state of logical replication
slots.

HISTORY

@@ -21,6 +21,7 @@
         repmgr: fix long node ID display in "cluster show" (Ian)
         repmgr: check for primary server before executing "witness register";
            GitHub #538 (Ian)
+        repmgr: "node check" will only consider physical replication slots (Ian)
         repmgrd: check binary and extension major versions match; GitHub #515 (Ian)
         repmgrd: on a cascaded standby, don't fail over if "failover=manual";
           GitHub #531 (Ian)

dbutils.c

@@ -3982,7 +3982,8 @@ get_free_replication_slot_count(PGconn *conn)
 	appendPQExpBufferStr(&query,
 						 " SELECT pg_catalog.current_setting('max_replication_slots')::INT - "
 						 "        pg_catalog.count(*) AS free_slots"
-						 "   FROM pg_catalog.pg_replication_slots");
+						 "   FROM pg_catalog.pg_replication_slots s"
+						 "  WHERE s.slot_type = 'physical'");
 
 	res = PQexec(conn, query.data);
 
@@ -4022,6 +4023,7 @@ get_inactive_replication_slots(PGconn *conn, KeyValueList *list)
 						 "   SELECT slot_name, slot_type "
 						 "     FROM pg_catalog.pg_replication_slots "
 						 "    WHERE active IS FALSE "
+						 "      AND slot_type = 'physical' "
 						 " ORDER BY slot_name ");
 
 	res = PQexec(conn, query.data);
@@ -4952,9 +4954,9 @@ get_node_replication_stats(PGconn *conn, t_node_info *node_info)
 	{
 		appendPQExpBufferStr(&query,
 							 "        current_setting('max_replication_slots')::INT AS max_replication_slots, "
-							 "        (SELECT pg_catalog.count(*) FROM pg_catalog.pg_replication_slots) AS total_replication_slots, "
+							 "        (SELECT pg_catalog.count(*) FROM pg_catalog.pg_replication_slots WHERE slot_type='physical') AS total_replication_slots, "
-							 "        (SELECT pg_catalog.count(*) FROM pg_catalog.pg_replication_slots WHERE active IS TRUE)  AS active_replication_slots, "
+							 "        (SELECT pg_catalog.count(*) FROM pg_catalog.pg_replication_slots WHERE active IS TRUE AND slot_type='physical')  AS active_replication_slots, "
-							 "        (SELECT pg_catalog.count(*) FROM pg_catalog.pg_replication_slots WHERE active IS FALSE) AS inactive_replication_slots, ");
+							 "        (SELECT pg_catalog.count(*) FROM pg_catalog.pg_replication_slots WHERE active IS FALSE AND slot_type='physical') AS inactive_replication_slots, ");
 	}
 
 

doc/appendix-release-notes.sgml

@@ -17,7 +17,7 @@
 
   <sect1 id="release-4.3">
     <title>Release 4.3</title>
-    <para><emphasis>Feb ???, 2019</emphasis></para>
+    <para><emphasis>Mar ???, 2019</emphasis></para>
     <para>
       &repmgr; 4.3 is a major release.
     </para>
@@ -214,6 +214,15 @@ REPMGRD_OPTS="--daemonize=false"</programlisting>
             </para>
 		  </listitem>
 
+          <listitem>
+            <para>
+              <command><link linkend="repmgr-node-check">repmgr node check</link></command>
+			  will only consider physical replication slots, as the purpose
+			  of slot checks is to warn about potential issues with
+			  streaming replication standbys which are no longer attached.
+			</para>
+		  </listitem>
+
         </itemizedlist>
       </para>
     </sect2>

doc/repmgr-node-check.sgml

@@ -18,6 +18,14 @@
       Performs some health checks on a node from a replication perspective.
       This command must be run on the local node.
     </para>
+	<note>
+	  <para>
+		Currently &repmgr; performs health checks on physical replication
+		slots only, with the aim of warning about streaming replication standbys which
+		have become detached and the associated risk of uncontrolled WAL file
+		growth.
+	  </para>
+	</note>
   </refsect1>
 
   <refsect1>
@@ -30,8 +38,8 @@
             Replication lag: OK (N/A - node is primary)
             WAL archiving: OK (0 pending files)
             Downstream servers: OK (2 of 2 downstream nodes attached)
-            Replication slots: OK (node has no replication slots)
+            Replication slots: OK (node has no physical replication slots)
-            Missing replication slots: OK (node has no missing replication slots)</programlisting>
+            Missing replication slots: OK (node has no missing physical replication slots)</programlisting>
     </para>
   </refsect1>
   <refsect1>
@@ -44,7 +52,7 @@
         OK (node is primary)</programlisting>
     </para>
     <para>
-   Parameters for individual checks are as follows:
+	  Parameters for individual checks are as follows:
     <itemizedlist spacing="compact" mark="bullet">
 
      <listitem>
@@ -76,13 +84,13 @@
 
      <listitem>
       <simpara>
-        <literal>--slots</literal>: checks there are no inactive replication slots
+        <literal>--slots</literal>: checks there are no inactive physical replication slots
       </simpara>
      </listitem>
 
      <listitem>
       <simpara>
-        <literal>--missing-slots</literal>: checks there are no missing replication slots
+        <literal>--missing-slots</literal>: checks there are no missing physical replication slots
       </simpara>
      </listitem>
 

repmgr-action-node.c

@@ -368,7 +368,7 @@ do_node_status(void)
 		initPQExpBuffer(&slotinfo);
 
 		appendPQExpBuffer(&slotinfo,
-						  "%i (of maximal %i; %i missing)",
+						  "%i physical (of maximal %i; %i missing)",
 						  node_info.active_replication_slots + node_info.inactive_replication_slots,
 						  node_info.max_replication_slots,
 						  missing_slots.node_count);
@@ -385,13 +385,13 @@ do_node_status(void)
 							  node_info.inactive_replication_slots);
 
 			item_list_append_format(&warnings,
-									_("- node has %i inactive replication slots"),
+									_("- node has %i inactive physical replication slots"),
 									node_info.inactive_replication_slots);
 
 			for (cell = inactive_replication_slots.head; cell; cell = cell->next)
 			{
 				item_list_append_format(&warnings,
-										"  - %s (%s)", cell->key, cell->value);
+										"  - %s", cell->key);
 			}
 
 			key_value_list_free(&inactive_replication_slots);
@@ -1639,12 +1639,12 @@ do_node_check_slots(PGconn *conn, OutputMode mode, t_node_info *node_info, Check
 	else if (node_info->total_replication_slots == 0)
 	{
 		appendPQExpBufferStr(&details,
-							 _("node has no replication slots"));
+							 _("node has no physical replication slots"));
 	}
 	else if (node_info->inactive_replication_slots == 0)
 	{
 		appendPQExpBuffer(&details,
-						  _("%i of %i replication slots are active"),
+						  _("%i of %i physical replication slots are active"),
 						  node_info->total_replication_slots,
 						  node_info->total_replication_slots);
 	}
@@ -1653,7 +1653,7 @@ do_node_check_slots(PGconn *conn, OutputMode mode, t_node_info *node_info, Check
 		status = CHECK_STATUS_CRITICAL;
 
 		appendPQExpBuffer(&details,
-						  _("%i of %i replication slots are inactive"),
+						  _("%i of %i physical replication slots are inactive"),
 						  node_info->inactive_replication_slots,
 						  node_info->total_replication_slots);
 	}
@@ -1721,7 +1721,7 @@ do_node_check_missing_slots(PGconn *conn, OutputMode mode, t_node_info *node_inf
 		if (missing_slots.node_count == 0)
 		{
 			appendPQExpBufferStr(&details,
-								 _("node has no missing replication slots"));
+								 _("node has no missing physical replication slots"));
 		}
 		else
 		{
@@ -1731,7 +1731,7 @@ do_node_check_missing_slots(PGconn *conn, OutputMode mode, t_node_info *node_inf
 			status = CHECK_STATUS_CRITICAL;
 
 			appendPQExpBuffer(&details,
-							  _("%i replication slots are missing"),
+							  _("%i physical replication slots are missing"),
 							  missing_slots.node_count);
 
 			if (missing_slots.node_count)
@@ -1792,7 +1792,7 @@ do_node_check_missing_slots(PGconn *conn, OutputMode mode, t_node_info *node_inf
 			if (list_output != NULL)
 			{
 				check_status_list_set(list_output,
-									  "Missing replication slots",
+									  "Missing physical replication slots",
 									  status,
 									  details.data);
 			}