Add a server version check to pg_basebackup and pg_receivexlog.

These programs don't work against 9.0 or earlier servers, so check that when
the connection is made. That's better than a cryptic error message you got
before.

Also, these programs won't work with a 9.3 server, because the WAL streaming
protocol was changed in a non-backwards-compatible way. As a general rule,
we don't make any guarantee that an old client will work with a new server,
so check that. However, allow a 9.1 client to connect to a 9.2 server, to
avoid breaking environments that currently work; a 9.1 client happens to
work with a 9.2 server, even though we didn't make any great effort to
ensure that.

This patch is for the 9.1 and 9.2 branches, I'll commit a similar patch to
master later. Although this isn't a critical bug fix, it seems safe enough
to back-patch. The error message you got when connecting to a 9.3devel
server without this patch was cryptic enough to warrant backpatching.

diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c
index bddd3718d44836854f2928aa1b6dd5e0409bee98..19cc9e864e378787fe727b39d7a3971abe0c829f 100644 (file)
--- a/src/bin/pg_basebackup/pg_basebackup.c
+++ b/src/bin/pg_basebackup/pg_basebackup.c
@@ -947,6 +947,9 @@ BaseBackup(void)
        int                     i;
        char            xlogstart[64];
        char            xlogend[64];
+       int                     minServerMajor,
+                               maxServerMajor;
+       int                     serverMajor;
 
        /*
         * Connect in replication mode to the server
@@ -956,6 +959,21 @@ BaseBackup(void)
                /* Error message already written in GetConnection() */
                exit(1);
 
+       /*
+        * Check server version. BASE_BACKUP command was introduced in 9.1, so
+        * we can't work with servers older than 9.1. And we don't support servers
+        * newer than the client.
+        */
+       minServerMajor = 901;
+       maxServerMajor = PG_VERSION_NUM / 100;
+       serverMajor = PQserverVersion(conn) / 100;
+       if (serverMajor < minServerMajor || serverMajor > maxServerMajor)
+       {
+               fprintf(stderr, _("%s: unsupported server version %s\n"),
+                               progname, PQparameterStatus(conn, "server_version"));
+               disconnect_and_exit(1);
+       }
+
        /*
         * Run IDENTIFY_SYSTEM so we can get the timeline
         */

diff --git a/src/bin/pg_basebackup/pg_receivexlog.c b/src/bin/pg_basebackup/pg_receivexlog.c
index 4d91addc56d6ea2b6978b86559372f204e883998..b7df693f2dd426e2fd0832ce172e4ded4e429c87 100644 (file)
--- a/src/bin/pg_basebackup/pg_receivexlog.c
+++ b/src/bin/pg_basebackup/pg_receivexlog.c
@@ -220,6 +220,9 @@ StreamLog(void)
        PGresult   *res;
        uint32          timeline;
        XLogRecPtr      startpos;
+       int                     minServerMajor,
+                               maxServerMajor;
+       int                     serverMajor;
 
        /*
         * Connect in replication mode to the server
@@ -229,6 +232,21 @@ StreamLog(void)
                /* Error message already written in GetConnection() */
                return;
 
+       /*
+        * Check server version. IDENTIFY_SYSTEM didn't return the current xlog
+        * position before 9.1, so we can't work with servers older than 9.1. And
+        * we don't support servers newer than the client.
+        */
+       minServerMajor = 901;
+       maxServerMajor = PG_VERSION_NUM / 100;
+       serverMajor = PQserverVersion(conn) / 100;
+       if (serverMajor < minServerMajor || serverMajor > maxServerMajor)
+       {
+               fprintf(stderr, _("%s: unsupported server version %s\n"),
+                               progname, PQparameterStatus(conn, "server_version"));
+               disconnect_and_exit(1);
+       }
+
        /*
         * Run IDENTIFY_SYSTEM so we can get the timeline and current xlog
         * position.