Revise test case added in 4374699.

Instead of using command_ok() to run psql, use safe_psql(). wrasse
isn't happy, and it be because of failure to pass -X to the psql
invocation, which safe_psql() will do automatically.

Since safe_psql() returns standard output instead of writing it to
a file, this requires some changes to the incantation for running
'diff'.

Test against the 'regression' database rather than 'postgres' so
we test more than just one table. That also means we need to record
the horizons later, after the test does "VACUUM FULL pg_largeobject".

Add an ORDER BY clause to the horizon query for stability.

Patch by me, reviewed by Tom Lane.

Discussion: http://postgr.es/m/CA+TgmoaGBbpzgu3=du1f9zDUbkfycO0y=_uWrLFy=KKEqXWeLQ@mail.gmail.com

Author: robertmhaas

src/bin/pg_upgrade/t/002_pg_upgrade.pl

@@ -161,27 +161,6 @@ sub generate_db
 	],
 	'dump before running pg_upgrade');
 
-# Also record the relfrozenxid and relminmxid horizons.
-my $horizon_query = <<EOM;
-SELECT
-  c.oid::regclass, c.relfrozenxid, c.relminmxid
-FROM
-  pg_class c, pg_namespace n
-WHERE
-  c.relnamespace = n.oid AND
-  ((n.nspname !~ '^pg_temp_' AND n.nspname !~ '^pg_toast_temp_' AND
-    n.nspname NOT IN ('pg_catalog', 'information_schema', 'binary_upgrade',
-                      'pg_toast'))
-  OR (n.nspname = 'pg_catalog' AND relname IN ('pg_largeobject')))
-EOM
-$horizon_query =~ s/\s+/ /g; # run it together on one line
-$newnode->command_ok(
-	[
-		'psql', '-At', '-d', $oldnode->connstr('postgres'),
-		'-o', "$tempdir/horizon1.txt", '-c', $horizon_query,
-	],
-	'horizons before running pg_upgrade');
-
 # After dumping, update references to the old source tree's regress.so
 # to point to the new tree.
 if (defined($ENV{oldinstall}))
@@ -231,6 +210,23 @@ sub generate_db
 
 $oldnode->safe_psql("regression", "VACUUM FULL pg_largeobject;");
 
+# Record the relfrozenxid and relminmxid horizons from the old server.
+my $horizon_query = <<EOM;
+SELECT
+  c.oid::regclass, c.relfrozenxid, c.relminmxid
+FROM
+  pg_class c, pg_namespace n
+WHERE
+  c.relnamespace = n.oid AND
+  ((n.nspname !~ '^pg_temp_' AND n.nspname !~ '^pg_toast_temp_' AND
+    n.nspname NOT IN ('pg_catalog', 'information_schema', 'binary_upgrade',
+                      'pg_toast'))
+  OR (n.nspname = 'pg_catalog' AND relname IN ('pg_largeobject')))
+ORDER BY c.oid::regclass::text
+EOM
+$horizon_query =~ s/\s+/ /g; # run it together on one line
+my $horizon1 = $oldnode->safe_psql('regression', $horizon_query);
+
 # In a VPATH build, we'll be started in the source directory, but we want
 # to run pg_upgrade in the build directory so that any files generated finish
 # in it, like delete_old_cluster.{sh,bat}.
@@ -315,13 +311,8 @@ sub generate_db
 	],
 	'dump after running pg_upgrade');
 
-# And second record of horizons as well.
-$newnode->command_ok(
-	[
-		'psql', '-At', '-d', $newnode->connstr('postgres'),
-		'-o', "$tempdir/horizon2.txt", '-c', $horizon_query,
-	],
-	'horizons after running pg_upgrade');
+# And record the horizons from the upgraded cluster as well.
+my $horizon2 = $newnode->safe_psql('regression', $horizon_query);
 
 # Compare the two dumps, there should be no differences.
 my $compare_res = compare("$tempdir/dump1.sql", "$tempdir/dump2.sql");
@@ -341,14 +332,21 @@ sub generate_db
 }
 
 # Compare the horizons, there should be no differences.
-$compare_res = compare("$tempdir/horizon1.txt", "$tempdir/horizon2.txt");
-is($compare_res, 0, 'old and new horizons match after pg_upgrade');
+my $horizons_ok = $horizon1 eq $horizon2;
+ok($horizons_ok, 'old and new horizons match after pg_upgrade');
 
 # Provide more context if the horizons do not match.
-if ($compare_res != 0)
+if (! $horizons_ok)
 {
+	# output is long, so use diff to compare
+	open my $fh, ">", "$tempdir/horizon1.txt" or die "could not open file: $!";
+	print $fh $horizon1;
+	close $fh;
+	open $fh, ">", "$tempdir/horizon2.txt" or die "could not open file: $!";
+	print $fh $horizon2;
 	my ($stdout, $stderr) =
-	  run_command([ 'diff', "$tempdir/horizon1.txt", "$tempdir/horizon2.txt" ]);
+		run_command([ 'diff', "$tempdir/horizon1.txt", "$tempdir/horizon2.txt" ]);
+	close $fh;
 	print "=== diff of $tempdir/horizon1.txt and $tempdir/horizon2.txt\n";
 	print "=== stdout ===\n";
 	print $stdout;