Rename standby_slot_names to synchronized_standby_slots.

The standby_slot_names GUC allows the specification of physical standby
slots that must be synchronized before the logical walsenders associated
with logical failover slots. However, for this purpose, the GUC name is
too generic.

Author: Hou Zhijie
Reviewed-by: Bertrand Drouvot, Masahiko Sawada
Backpatch-through: 17
Discussion: https://postgr.es/m/ZnWeUgdHong93fQN@momjian.us

Author: Amit Kapila

doc/src/sgml/config.sgml

@@ -4569,10 +4569,10 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
       </listitem>
      </varlistentry>
 
-     <varlistentry id="guc-standby-slot-names" xreflabel="standby_slot_names">
-      <term><varname>standby_slot_names</varname> (<type>string</type>)
+     <varlistentry id="guc-synchronized-standby-slots" xreflabel="synchronized_standby_slots">
+      <term><varname>synchronized_standby_slots</varname> (<type>string</type>)
       <indexterm>
-       <primary><varname>standby_slot_names</varname> configuration parameter</primary>
+       <primary><varname>synchronized_standby_slots</varname> configuration parameter</primary>
       </indexterm>
       </term>
       <listitem>
@@ -4587,7 +4587,7 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
         after the standby is promoted, the physical replication slot for the
         standby should be listed here. Note that logical replication will not
         proceed if the slots specified in the
-        <varname>standby_slot_names</varname> do not exist or are invalidated.
+        <varname>synchronized_standby_slots</varname> do not exist or are invalidated.
         Additionally, the replication management functions
         <link linkend="pg-replication-slot-advance">
         <function>pg_replication_slot_advance</function></link>,
@@ -4596,12 +4596,12 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
         <link linkend="pg-logical-slot-peek-changes">
         <function>pg_logical_slot_peek_changes</function></link>,
         when used with logical failover slots, will block until all
-        physical slots specified in <varname>standby_slot_names</varname> have
+        physical slots specified in <varname>synchronized_standby_slots</varname> have
         confirmed WAL receipt.
        </para>
        <para>
         The standbys corresponding to the physical replication slots in
-        <varname>standby_slot_names</varname> must configure
+        <varname>synchronized_standby_slots</varname> must configure
         <literal>sync_replication_slots = true</literal> so they can receive
         logical failover slot changes from the primary.
        </para>

doc/src/sgml/func.sgml

@@ -29057,7 +29057,7 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
         adding the rows produced when decoding each new transaction commit.
         If the specified slot is a logical failover slot then the function will
         not return until all physical slots specified in
-        <link linkend="guc-standby-slot-names"><varname>standby_slot_names</varname></link>
+        <link linkend="guc-synchronized-standby-slots"><varname>synchronized_standby_slots</varname></link>
         have confirmed WAL receipt.
        </para></entry>
       </row>
@@ -29137,7 +29137,7 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
         slot may return to an earlier position. If the specified slot is a
         logical failover slot then the function will not return until all
         physical slots specified in
-        <link linkend="guc-standby-slot-names"><varname>standby_slot_names</varname></link>
+        <link linkend="guc-synchronized-standby-slots"><varname>synchronized_standby_slots</varname></link>
         have confirmed WAL receipt.
        </para></entry>
       </row>

doc/src/sgml/logical-replication.sgml

@@ -713,7 +713,7 @@ ALTER SUBSCRIPTION
    server before the failover happens. To ensure a successful failover, the
    standby server must be ahead of the subscriber. This can be achieved by
    configuring
-   <link linkend="guc-standby-slot-names"><varname>standby_slot_names</varname></link>.
+   <link linkend="guc-synchronized-standby-slots"><varname>synchronized_standby_slots</varname></link>.
   </para>
 
   <para>

doc/src/sgml/logicaldecoding.sgml

@@ -385,16 +385,16 @@ postgres=# select * from pg_logical_slot_get_changes('regression_slot', NULL, NU
      <literal>dbname</literal> in the
      <link linkend="guc-primary-conninfo"><varname>primary_conninfo</varname></link>.
      It's highly recommended that the said physical replication slot is named in
-     <link linkend="guc-standby-slot-names"><varname>standby_slot_names</varname></link>
+     <link linkend="guc-synchronized-standby-slots"><varname>synchronized_standby_slots</varname></link>
      list on the primary, to prevent the subscriber from consuming changes
      faster than the hot standby. Even when correctly configured, some latency
      is expected when sending changes to logical subscribers due to the waiting
      on slots named in
-     <link linkend="guc-standby-slot-names"><varname>standby_slot_names</varname></link>.
-     When <varname>standby_slot_names</varname> is utilized, the
+     <link linkend="guc-synchronized-standby-slots"><varname>synchronized_standby_slots</varname></link>.
+     When <varname>synchronized_standby_slots</varname> is utilized, the
      primary server will not completely shut down until the corresponding
      standbys, associated with the physical replication slots specified
-     in <varname>standby_slot_names</varname>, have confirmed
+     in <varname>synchronized_standby_slots</varname>, have confirmed
      receiving the WAL up to the latest flushed position on the primary server.
     </para>
 

src/backend/replication/logical/slotsync.c

@@ -620,8 +620,8 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid)
 	if (remote_slot->confirmed_lsn > latestFlushPtr)
 	{
 		/*
-		 * Can get here only if GUC 'standby_slot_names' on the primary server
-		 * was not configured correctly.
+		 * Can get here only if GUC 'synchronized_standby_slots' on the
+		 * primary server was not configured correctly.
 		 */
 		ereport(AmLogicalSlotSyncWorkerProcess() ? LOG : ERROR,
 				errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),