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 90060d0f8ebf7a358e558d5d002e6b1b65320056..ee0ace082ca17ffeed05e78bc87f34e326a5fc8f 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",
                          new_cluster.bindir, cluster_conn_opts(&old_cluster),
+                         protocol_negotiation_supported(&old_cluster) ? "" : " -d \"max_protocol_version=3.0\"",
                          log_opts.verbose ? "--verbose" : "",
                          GLOBALS_DUMP_FILE);
        check_ok();
@@ -42,6 +43,9 @@ 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 e647e71ecaf40a0216e82d037dadca3bfed04470..14f9cb522db9da6c31d66cca76c0c1b6eb2c4af4 100644 (file)
--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -446,6 +446,7 @@ 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           new_9_0_populate_pg_largeobject_metadata(ClusterInfo *cluster,
                                                                                                         bool check_mode);
 void           old_9_3_check_for_line_data_type_usage(ClusterInfo *cluster);

diff --git a/src/bin/pg_upgrade/server.c b/src/bin/pg_upgrade/server.c
index 7fed0ae1086dc30edabae41d8372f90a1edbcd44..f49f3013c381d4091f1d229021ae5f7128efc5c5 100644 (file)
--- a/src/bin/pg_upgrade/server.c
+++ b/src/bin/pg_upgrade/server.c
@@ -70,6 +70,8 @@ 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 ccb012657be7cba83bc39e656f9f748d8be1bac5..be861157bfe410c59bbae645815dfb6a0c130a83 100644 (file)
--- a/src/bin/pg_upgrade/version.c
+++ b/src/bin/pg_upgrade/version.c
@@ -325,6 +325,37 @@ 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