pg_upgrade: Use max_protocol_version=3.0 for older servers

The grease patch in 4966bd3ed found its first problem: prior to the
February 2018 patch releases, no server knew how to negotiate protocol
versions, so pg_upgrade needs to take that into account when speaking to
those older servers.

This will be true even after the grease feature is reverted; we don't
need anyone to trip over this again in the future. Backpatch so that all
supported versions of pg_upgrade can gracefully handle an update to the
default protocol version. (This is needed for any distributions that
link older binaries against newer libpqs, such as Debian.) Branches
prior to 18 need an additional version check, for the existence of
max_protocol_version.

Per buildfarm member crake.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CAOYmi%2B%3D4QhCjssfNEoZVK8LPtWxnfkwT5p-PAeoxtG9gpNjqOQ%40mail.gmail.com
Backpatch-through: 14

diff --git a/src/bin/pg_upgrade/dump.c b/src/bin/pg_upgrade/dump.c
index 29b9e44f78268a3bcb75d46c5e465edffd2bc7d3..f7d6a537b4fcefc87e0a15c4a1fbbe5a9e0b5f6c 100644 (file)
--- a/src/bin/pg_upgrade/dump.c
+++ b/src/bin/pg_upgrade/dump.c
@@ -21,9 +21,10 @@ generate_old_dump(void)
 
        /* run new pg_dumpall binary for globals */
        exec_prog(UTILITY_LOG_FILE, NULL, true, true,
-                         "\"%s/pg_dumpall\" %s --globals-only --quote-all-identifiers "
+                         "\"%s/pg_dumpall\" %s%s --globals-only --quote-all-identifiers "
                          "--binary-upgrade %s -f \"%s/%s\"",
                          new_cluster.bindir, cluster_conn_opts(&old_cluster),
+                         protocol_negotiation_supported(&old_cluster) ? "" : " -d \"max_protocol_version=3.0\"",
                          log_opts.verbose ? "--verbose" : "",
                          log_opts.dumpdir,
                          GLOBALS_DUMP_FILE);
@@ -43,6 +44,9 @@ generate_old_dump(void)
                initPQExpBuffer(&connstr);
                appendPQExpBufferStr(&connstr, "dbname=");
                appendConnStrVal(&connstr, old_db->db_name);
+               if (!protocol_negotiation_supported(&old_cluster))
+                       appendPQExpBufferStr(&connstr, " max_protocol_version=3.0");
+
                initPQExpBuffer(&escaped_connstr);
                appendShellString(&escaped_connstr, connstr.data);
                termPQExpBuffer(&connstr);

diff --git a/src/bin/pg_upgrade/pg_upgrade.h b/src/bin/pg_upgrade/pg_upgrade.h
index 19ca68ed619f13df70f2715c5da74f0bcd9dc080..803acc696efd1192f3d4827dc06b566ee6aa9873 100644 (file)
--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -449,6 +449,7 @@ bool                check_for_data_types_usage(ClusterInfo *cluster,
 bool           check_for_data_type_usage(ClusterInfo *cluster,
                                                                          const char *type_name,
                                                                          const char *output_path);
+bool           protocol_negotiation_supported(const ClusterInfo *cluster);
 void           old_9_3_check_for_line_data_type_usage(ClusterInfo *cluster);
 void           old_9_6_check_for_unknown_data_type_usage(ClusterInfo *cluster);
 void           old_9_6_invalidate_hash_indexes(ClusterInfo *cluster,

diff --git a/src/bin/pg_upgrade/server.c b/src/bin/pg_upgrade/server.c
index 265137e86bf97fa179de68847f5e14c5a33dfb22..df165efac4054fa59d62bfdeb7908c2b8580bae2 100644 (file)
--- a/src/bin/pg_upgrade/server.c
+++ b/src/bin/pg_upgrade/server.c
@@ -71,6 +71,8 @@ get_db_conn(ClusterInfo *cluster, const char *db_name)
                appendPQExpBufferStr(&conn_opts, " host=");
                appendConnStrVal(&conn_opts, cluster->sockdir);
        }
+       if (!protocol_negotiation_supported(cluster))
+               appendPQExpBufferStr(&conn_opts, " max_protocol_version=3.0");
 
        conn = PQconnectdb(conn_opts.data);
        termPQExpBuffer(&conn_opts);

diff --git a/src/bin/pg_upgrade/version.c b/src/bin/pg_upgrade/version.c
index 20c61072a425376327be6fadcb26972718109f62..8658436b36691b95d3cf7fb9a14469644fc1f3c3 100644 (file)
--- a/src/bin/pg_upgrade/version.c
+++ b/src/bin/pg_upgrade/version.c
@@ -241,6 +241,37 @@ old_9_6_check_for_unknown_data_type_usage(ClusterInfo *cluster)
                check_ok();
 }
 
+/*
+ * Older servers can't support newer protocol versions, so their connection
+ * strings will need to lock max_protocol_version to 3.0.
+ */
+bool
+protocol_negotiation_supported(const ClusterInfo *cluster)
+{
+       /*
+        * Back-branch-specific complication: in libpq versions prior to PG18,
+        * max_protocol_version isn't supported. But we also don't need to worry
+        * about newer protocol versions being used in that case, so just lie and
+        * return true.
+        *
+        * (Checking for a libpq version that's newer than this branch looks very
+        * strange, but distributions are allowed to link older pg_upgrade
+        * binaries against the newest release of libpq.)
+        */
+       if (PQlibVersion() < 180000)
+               return true;
+
+       /*
+        * The February 2018 patch release (9.3.21, 9.4.16, 9.5.11, 9.6.7, and
+        * 10.2) added support for NegotiateProtocolVersion. But ClusterInfo only
+        * has information about the major version number. To ensure we can still
+        * upgrade older unpatched servers, just assume anything prior to PG11
+        * can't negotiate. It's not possible for those servers to make use of
+        * newer protocols anyway, so nothing is lost.
+        */
+       return (GET_MAJOR_VERSION(cluster->major_version) >= 1100);
+}
+
 /*
  * old_9_6_invalidate_hash_indexes()
  *     9.6 -> 10