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 6c8c82dca89a17cfd39b0e59eac6f355a9ee0d3b..a698519029e541d4905c65051e767e34135c5dff 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 7afa96716ec781cdedea77b2f4eb2600496991ac..44aad96de7bbecdbbb4d02ef7ff7cd77f36b795b 100644 (file)
--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -456,6 +456,7 @@ 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 0bc3d2806b87095578b825ea9dff2b459a0e5704..75d40626b485fec5ea2c9d91414a066b85945967 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 403a6d7cfaaf340bf235777f3ad761a723ff6226..ff5020ba6646448918e73906283144b58e25b08c 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