better-psql-invocation.txt

diff --git a/src/bin/pg_upgrade/t/002_pg_upgrade.pl b/src/bin/pg_upgrade/t/002_pg_upgrade.pl
index 09af8157d0..a8df6440a4 100644
--- a/src/bin/pg_upgrade/t/002_pg_upgrade.pl
+++ b/src/bin/pg_upgrade/t/002_pg_upgrade.pl
@@ -173,14 +173,10 @@ WHERE
     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
 $horizon_query =~ s/\s+/ /g; # run it together on one line
-$newnode->command_ok(
-	[
-		'psql', '-At', '-d', $oldnode->connstr('postgres'),
-		'-o', "$tempdir/horizon1.txt", '-c', $horizon_query,
-	],
-	'horizons before running pg_upgrade');
+my $horizon1 = $oldnode->safe_psql('regression', $horizon_query);
 
 # After dumping, update references to the old source tree's regress.so
 # to point to the new tree.
@@ -316,12 +312,7 @@ $newnode->command_ok(
 	'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');
+my $horizon2 = $newnode->safe_psql('regression', $horizon_query);
 
 # Compare the two dumps, there should be no differences.
 my $compare_res = compare("$tempdir/dump1.sql", "$tempdir/dump2.sql");
@@ -341,14 +332,21 @@ if ($compare_res != 0)
 }
 
 # 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;