On 7/2/15 3:37 AM, Michael Paquier wrote:
> Regarding patch 3, I have more comments:
> 1) I think that documentation should clearly mention that if -R and -S
> are used together, a primary_slot_name entry is added in the
> recovery.conf generated with the slot name defined.

Updated proposal attached.

> 2)
>  sub psql
>  {
>         my ($dbname, $sql) = @_;
> -       run [ 'psql', '-X', '-q', '-d', $dbname, '-f', '-' ], '<', \$sql or 
> die;
> +       my ($stdout, $stderr);
> +       run [ 'psql', '-X', '-A', '-t', '-q', '-d', $dbname, '-f', '-'
> ], '<', \$sql, '>', \$stdout, '2>', \$stderr or die;
> +       chomp $stdout;
> +       return $stdout;
>  }
> RewindTest.pm has a routine called check_query defined. I would be
> great to extend a bit more psql than what I thought previously by
> returning from it ($result, $stdout, $strerr) and make check_query
> directly use it. This way we have a unique interface to run psql and
> capture output. I don't mind writing this refactoring patch on top of
> your set if that's necessary.

Let's do that as a separate patch.  Adding multiple return values makes
calling awkward, so I'd like to sort out the actual use cases before we
do that.

> 3)
> +command_ok([ 'pg_basebackup', '-D', "$tempdir/backupxs_sl_R", '-X',
> 'stream', '-S', 'slot1', '-R' ],
> +       'pg_basebackup with replication slot and -R runs');
> +$recovery_conf = slurp_file "$tempdir/backupR/recovery.conf";
> +like(slurp_file("$tempdir/backupxs_sl_R/recovery.conf"),
> slurp_file is slurping an incorrect file and $recovery_conf is used
> nowhere after, so you could simply remove this line.

Yeah, that was some leftover garbage.

>From 7ecb1794c2aaeea9753af07e2f54f6e483af255f Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pete...@gmx.net>
Date: Tue, 21 Jul 2015 21:06:45 -0400
Subject: [PATCH 3/3] pg_basebackup: Add --slot option

This option specifies a replication slot for WAL streaming (-X stream),
so that there can be continuous replication slot use between WAL
streaming during the base backup and the start of regular streaming
replication.
---
 doc/src/sgml/ref/pg_basebackup.sgml          | 27 ++++++++++++++++++++++++---
 src/bin/pg_basebackup/pg_basebackup.c        | 24 +++++++++++++++++++++++-
 src/bin/pg_basebackup/t/010_pg_basebackup.pl | 22 +++++++++++++++++++++-
 src/test/perl/TestLib.pm                     |  5 ++++-
 4 files changed, 72 insertions(+), 6 deletions(-)

diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml
index cb8b8a3..5f8b9b7 100644
--- a/doc/src/sgml/ref/pg_basebackup.sgml
+++ b/doc/src/sgml/ref/pg_basebackup.sgml
@@ -215,15 +215,36 @@ <title>Options</title>
       <listitem>
 
        <para>
-        Write a minimal <filename>recovery.conf</filename> in the output directory (or into
-        the base archive file when using tar format) to ease setting
-        up a standby server.
+        Write a minimal <filename>recovery.conf</filename> in the output
+        directory (or into the base archive file when using tar format) to
+        ease setting up a standby server.
+        The <filename>recovery.conf</filename> file will record the connection
+        settings and, if specified, the replication slot
+        that <application>pg_basebackup</application> is using, so that the
+        streaming replication will use the same settings later on.
        </para>
 
       </listitem>
      </varlistentry>
 
      <varlistentry>
+      <term><option>-S <replaceable>slotname</replaceable></option></term>
+      <term><option>--slot=<replaceable class="parameter">slotname</replaceable></option></term>
+      <listitem>
+       <para>
+        This option can only be used together with <literal>-X
+        stream</literal>.  It causes the WAL streaming to use the specified
+        replication slot.  If the base backup is intended to be used as a
+        streaming replication standby using replication slots, it should then
+        use the same replication slot name
+        in <filename>recovery.conf</filename>.  That way, it is ensured that
+        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>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>-T <replaceable class="parameter">olddir</replaceable>=<replaceable class="parameter">newdir</replaceable></option></term>
       <term><option>--tablespace-mapping=<replaceable class="parameter">olddir</replaceable>=<replaceable class="parameter">newdir</replaceable></option></term>
       <listitem>
diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c
index 5363680..80de882 100644
--- a/src/bin/pg_basebackup/pg_basebackup.c
+++ b/src/bin/pg_basebackup/pg_basebackup.c
@@ -239,6 +239,7 @@ usage(void)
 	  "                         (in kB/s, or use suffix \"k\" or \"M\")\n"));
 	printf(_("  -R, --write-recovery-conf\n"
 			 "                         write recovery.conf after backup\n"));
+	printf(_("  -S, --slot=SLOTNAME    replication slot to use\n"));
 	printf(_("  -T, --tablespace-mapping=OLDDIR=NEWDIR\n"
 	  "                         relocate tablespace in OLDDIR to NEWDIR\n"));
 	printf(_("  -x, --xlog             include required WAL files in backup (fetch mode)\n"));
@@ -1536,6 +1537,13 @@ GenerateRecoveryConf(PGconn *conn)
 	appendPQExpBuffer(recoveryconfcontents, "primary_conninfo = '%s'\n", escaped);
 	free(escaped);
 
+	if (replication_slot)
+	{
+		escaped = escape_quotes(replication_slot);
+		appendPQExpBuffer(recoveryconfcontents, "primary_slot_name = '%s'\n", replication_slot);
+		free(escaped);
+	}
+
 	if (PQExpBufferBroken(recoveryconfcontents) ||
 		PQExpBufferDataBroken(conninfo_buf))
 	{
@@ -1934,6 +1942,7 @@ main(int argc, char **argv)
 		{"checkpoint", required_argument, NULL, 'c'},
 		{"max-rate", required_argument, NULL, 'r'},
 		{"write-recovery-conf", no_argument, NULL, 'R'},
+		{"slot", required_argument, NULL, 'S'},
 		{"tablespace-mapping", required_argument, NULL, 'T'},
 		{"xlog", no_argument, NULL, 'x'},
 		{"xlog-method", required_argument, NULL, 'X'},
@@ -1974,7 +1983,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:F:r:RT:xX:l:zZ:d:c:h:p:U:s:wWvP",
+	while ((c = getopt_long(argc, argv, "D:F:r:RT:xX:l:zZ:d:c:h:p:U:s:S:wWvP",
 							long_options, &option_index)) != -1)
 	{
 		switch (c)
@@ -2001,6 +2010,9 @@ main(int argc, char **argv)
 			case 'R':
 				writerecoveryconf = true;
 				break;
+			case 'S':
+				replication_slot = pg_strdup(optarg);
+				break;
 			case 'T':
 				tablespace_list_append(optarg);
 				break;
@@ -2165,6 +2177,16 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (replication_slot && !streamwal)
+	{
+		fprintf(stderr,
+				_("%s: replication slots can only be used with WAL streaming\n"),
+				progname);
+		fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
+				progname);
+		exit(1);
+	}
+
 	if (strcmp(xlog_dir, "") != 0)
 	{
 		if (format != 'p')
diff --git a/src/bin/pg_basebackup/t/010_pg_basebackup.pl b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
index bf9fdcf..b605fa9 100644
--- a/src/bin/pg_basebackup/t/010_pg_basebackup.pl
+++ b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
@@ -2,7 +2,7 @@
 use warnings;
 use Cwd;
 use TestLib;
-use Test::More tests => 44;
+use Test::More tests => 51;
 
 program_help_ok('pg_basebackup');
 program_version_ok('pg_basebackup');
@@ -37,6 +37,7 @@
 	'pg_basebackup fails because of WAL configuration');
 
 open CONF, ">>$tempdir/pgdata/postgresql.conf";
+print CONF "max_replication_slots = 10\n";
 print CONF "max_wal_senders = 10\n";
 print CONF "wal_level = archive\n";
 close CONF;
@@ -156,3 +157,22 @@
 command_ok([ 'pg_basebackup', '-D', "$tempdir/backupxs", '-X', 'stream' ],
 	'pg_basebackup -X stream runs');
 ok(grep(/^[0-9A-F]{24}$/, slurp_dir("$tempdir/backupxf/pg_xlog")), 'WAL files copied');
+
+command_fails([ 'pg_basebackup', '-D', "$tempdir/fail", '-S', 'slot1' ],
+	'pg_basebackup with replication slot fails without -X stream');
+command_fails([ 'pg_basebackup', '-D', "$tempdir/backupxs_sl_fail", '-X', 'stream', '-S', 'slot1' ],
+	'pg_basebackup fails with nonexistent replication slot');
+
+psql 'postgres', q{SELECT * FROM pg_create_physical_replication_slot('slot1')};
+my $lsn = psql 'postgres', q{SELECT restart_lsn FROM pg_replication_slots WHERE slot_name = 'slot1'};
+is($lsn, '', 'restart LSN of new slot is null');
+command_ok([ 'pg_basebackup', '-D', "$tempdir/backupxs_sl", '-X', 'stream', '-S', 'slot1' ],
+	'pg_basebackup -X stream with replication slot runs');
+$lsn = psql 'postgres', q{SELECT restart_lsn FROM pg_replication_slots WHERE slot_name = 'slot1'};
+like($lsn, qr!^0/[0-9A-Z]{8}$!, 'restart LSN of slot has advanced');
+
+command_ok([ 'pg_basebackup', '-D', "$tempdir/backupxs_sl_R", '-X', 'stream', '-S', 'slot1', '-R' ],
+	'pg_basebackup with replication slot and -R runs');
+like(slurp_file("$tempdir/backupxs_sl_R/recovery.conf"),
+	 qr/^primary_slot_name = 'slot1'$/m,
+	 'recovery.conf sets primary_slot_name');
diff --git a/src/test/perl/TestLib.pm b/src/test/perl/TestLib.pm
index ca91be9..4fcf8b9 100644
--- a/src/test/perl/TestLib.pm
+++ b/src/test/perl/TestLib.pm
@@ -168,8 +168,11 @@ END
 sub psql
 {
 	my ($dbname, $sql) = @_;
+	my ($stdout, $stderr);
 	print("# Running SQL command: $sql\n");
-	run [ 'psql', '-X', '-q', '-d', $dbname, '-f', '-' ], '<', \$sql or die;
+	run [ 'psql', '-X', '-A', '-t', '-q', '-d', $dbname, '-f', '-' ], '<', \$sql, '>', \$stdout, '2>', \$stderr or die;
+	chomp $stdout;
+	return $stdout;
 }
 
 sub slurp_dir
-- 
2.4.6

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