Make pg_basebackup work with pre-9.3 servers, and add server version check.

A new 'starttli' field was added to the response of BASE_BACKUP command.
Make pg_basebackup tolerate the case that it's missing, so that it still
works with older servers.

Add an explicit check for the server version, so that you get a nicer error
message if you try to use it with a pre-9.1 server.

The streaming protocol message format changed in 9.3, so -X stream still won't
work with pre-9.3 servers. I added a version check to ReceiveXLogStream()
earlier, but write that slightly differently, so that in 9.4, it will still
work with a 9.3 server. (In 9.4, the error message needs to be adjusted to
"9.3 or above", though). Also, if the version check fails, don't retry.

1 files changed, 6 insertions, 0 deletions

diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml
index 578541a1e2a..9fe440a66de 100644
--- a/doc/src/sgml/ref/pg_basebackup.sgml
+++ b/doc/src/sgml/ref/pg_basebackup.sgml
@@ -520,6 +520,12 @@ PostgreSQL documentation
    for all additional tablespaces must be identical whenever a backup is
    restored. The main data directory, however, is relocatable to any location.
   </para>
+
+  <para>
+   <application>pg_basebackup</application> works with servers of the same
+   or an older major version, down to 9.1. However, WAL streaming mode (-X
+   stream) only works with server version 9.3.
+  </para>
  </refsect1>
 
  <refsect1>