From 818fdc00c0f0f9d98082830c4e9fdc40e9083859 Mon Sep 17 00:00:00 2001
From: Craig Ringer <craig@2ndquadrant.com>
Date: Mon, 29 Aug 2016 11:31:52 +0800
Subject: [PATCH 1/2] Report server_version_num alongside server_version in
 startup packet

We expose PG_VERSION_NUM in Makefiles and headers and in pg_settings,
but the equivalent server_version_num isn't sent in the startup packet
so clients must rely on parsing the server_version. Make
server_version_num GUC_REPORT so clients can use server_version_num if
present and fall back to server_version for older PostgreSQL versions.
---
 doc/src/sgml/libpq.sgml      | 6 ++++--
 doc/src/sgml/protocol.sgml   | 4 +++-
 src/backend/utils/misc/guc.c | 2 +-
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 2f9350b..5428282 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -1632,6 +1632,7 @@ const char *PQparameterStatus(const PGconn *conn, const char *paramName);
       <para>
        Parameters reported as of the current release include
        <varname>server_version</>,
+       <varname>server_version_num</>,
        <varname>server_encoding</>,
        <varname>client_encoding</>,
        <varname>application_name</>,
@@ -1647,9 +1648,10 @@ const char *PQparameterStatus(const PGconn *conn, const char *paramName);
        <varname>standard_conforming_strings</> was not reported by releases
        before 8.1;
        <varname>IntervalStyle</> was not reported by releases before 8.4;
-       <varname>application_name</> was not reported by releases before 9.0.)
+       <varname>application_name</> was not reported by releases before 9.0;
+       <varname>server_version_num</> was not reported by releases before 10.0.)
        Note that
-       <varname>server_version</>,
+       <varname>server_version</>, <varname>server_version_num</>,
        <varname>server_encoding</> and
        <varname>integer_datetimes</>
        cannot change after startup.
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 68b0941..12431dc 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -1091,6 +1091,7 @@
     At present there is a hard-wired set of parameters for which
     ParameterStatus will be generated: they are
     <varname>server_version</>,
+    <varname>server_version_num</>,
     <varname>server_encoding</>,
     <varname>client_encoding</>,
     <varname>application_name</>,
@@ -1106,7 +1107,8 @@
     <varname>standard_conforming_strings</> was not reported by releases
     before 8.1;
     <varname>IntervalStyle</> was not reported by releases before 8.4;
-    <varname>application_name</> was not reported by releases before 9.0.)
+    <varname>application_name</> was not reported by releases before 9.0;
+    <varname>server_version_num</> was not reported by releases before 10.0.)
     Note that
     <varname>server_version</>,
     <varname>server_encoding</> and
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index c5178f7..36e3604 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2767,7 +2767,7 @@ static struct config_int ConfigureNamesInt[] =
 		{"server_version_num", PGC_INTERNAL, PRESET_OPTIONS,
 			gettext_noop("Shows the server version as an integer."),
 			NULL,
-			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_REPORT
 		},
 		&server_version_num,
 		PG_VERSION_NUM, PG_VERSION_NUM, PG_VERSION_NUM,
-- 
2.5.5