Make pg_basebackup use temporary replication slots

Temporary replication slots will be used by default when wal streaming
is used and no slot name is specified with -S. If a slot name is
specified, then a permanent slot with that name is used. If --no-slot is
specified, then no permanent or temporary slot will be used.

Temporary slots are only used on 10.0 and newer, of course.

1 files changed, 25 insertions, 0 deletions

diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml
index ba7d16abf04..5c2db2581c3 100644
--- a/doc/src/sgml/ref/pg_basebackup.sgml
+++ b/doc/src/sgml/ref/pg_basebackup.sgml
@@ -240,6 +240,31 @@ PostgreSQL documentation
         the server does not remove any necessary WAL data in the time between
         the end of the base backup and the start of streaming replication.
        </para>
+       <para>
+        If this option is not specified and the server supports temporary
+        replication slots (version 10 and later), then a temporary replication
+        slot is automatically used for WAL streaming.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>--no-slot</option></term>
+      <listitem>
+       <para>
+        This option prevents the creation of a temporary replication slot
+        during the backup even if it's supported by the server.
+       </para>
+       <para>
+        Temporary replication slots are created by default if no slot name
+        is given with the option <option>-S</option> when using log streaming.
+       </para>
+       <para>
+        The main purpose of this option is to allow taking a base backup when
+        the server is out of free replication slots.  Using replication slots
+        is almost always preferred, because it prevents needed WAL from being
+        removed by the server during the backup.
+       </para>
       </listitem>
      </varlistentry>