postgres
diff --git a/‎src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm
+293 b/‎src/test/perl/PostgreSQL/Test/AdjustUpgrade.pm
+293
@@ -0,0 +1,293 @@
+
+# Copyright (c) 2023, PostgreSQL Global Development Group
+
+=pod
+
+=head1 NAME
+
+PostgreSQL::Test::AdjustUpgrade - helper module for cross-version upgrade tests
+
+=head1 SYNOPSIS
+
+  use PostgreSQL::Test::AdjustUpgrade;
+
+  # Build commands to adjust contents of old-version database before dumping
+  $statements = adjust_database_contents($old_version, %dbnames);
+
+  # Adjust contents of old pg_dumpall output file to match newer version
+  $dump = adjust_old_dumpfile($old_version, $dump);
+
+  # Adjust contents of new pg_dumpall output file to match older version
+  $dump = adjust_new_dumpfile($old_version, $dump);
+
+=head1 DESCRIPTION
+
+C<PostgreSQL::Test::AdjustUpgrade> encapsulates various hacks needed to
+compare the results of cross-version upgrade tests.
+
+=cut
+
+package PostgreSQL::Test::AdjustUpgrade;
+
+use strict;
+use warnings;
+
+use Exporter 'import';
+use PostgreSQL::Version;
+
+our @EXPORT = qw(
+  adjust_database_contents
+  adjust_old_dumpfile
+  adjust_new_dumpfile
+);
+
+=pod
+
+=head1 ROUTINES
+
+=over
+
+=item $statements = adjust_database_contents($old_version, %dbnames)
+
+Generate SQL commands to perform any changes to an old-version installation
+that are needed before we can pg_upgrade it into the current PostgreSQL
+version.
+
+Typically this involves dropping or adjusting no-longer-supported objects.
+
+Arguments:
+
+=over
+
+=item C<old_version>: Branch we are upgrading from, represented as a
+PostgreSQL::Version object.
+
+=item C<dbnames>: Hash of database names present in the old installation.
+
+=back
+
+Returns a reference to a hash, wherein the keys are database names and the
+values are arrayrefs to lists of statements to be run in those databases.
+
+=cut
+
+sub adjust_database_contents
+{
+	my ($old_version, %dbnames) = @_;
+	my $result = {};
+
+	# remove dbs of modules known to cause pg_upgrade to fail
+	# anything not builtin and incompatible should clean up its own db
+	foreach my $bad_module ('test_ddl_deparse', 'tsearch2')
+	{
+		if ($dbnames{"contrib_regression_$bad_module"})
+		{
+			_add_st($result, 'postgres',
+				"drop database contrib_regression_$bad_module");
+			delete($dbnames{"contrib_regression_$bad_module"});
+		}
+	}
+
+	# avoid version number issues with test_ext7
+	if ($dbnames{contrib_regression_test_extensions})
+	{
+		_add_st(
+			$result,
+			'contrib_regression_test_extensions',
+			'drop extension if exists test_ext7');
+	}
+
+	# get rid of dblink's dependencies on regress.so
+	my $regrdb =
+	  $old_version le '9.4'
+	  ? 'contrib_regression'
+	  : 'contrib_regression_dblink';
+
+	if ($dbnames{$regrdb})
+	{
+		_add_st(
+			$result, $regrdb,
+			'drop function if exists public.putenv(text)',
+			'drop function if exists public.wait_pid(integer)');
+	}
+
+	return $result;
+}
+
+# Internal subroutine to add statement(s) to the list for the given db.
+sub _add_st
+{
+	my ($result, $db, @st) = @_;
+
+	$result->{$db} ||= [];
+	push(@{ $result->{$db} }, @st);
+}
+
+=pod
+
+=item adjust_old_dumpfile($old_version, $dump)
+
+Edit a dump output file, taken from the adjusted old-version installation
+by current-version C<pg_dumpall -s>, so that it will match the results of
+C<pg_dumpall -s> on the pg_upgrade'd installation.
+
+Typically this involves coping with cosmetic differences in the output
+of backend subroutines used by pg_dump.
+
+Arguments:
+
+=over
+
+=item C<old_version>: Branch we are upgrading from, represented as a
+PostgreSQL::Version object.
+
+=item C<dump>: Contents of dump file
+
+=back
+
+Returns the modified dump text.
+
+=cut
+
+sub adjust_old_dumpfile
+{
+	my ($old_version, $dump) = @_;
+
+	# use Unix newlines
+	$dump =~ s/\r\n/\n/g;
+
+	# Version comments will certainly not match.
+	$dump =~ s/^-- Dumped from database version.*\n//mg;
+
+	if ($old_version lt '9.3')
+	{
+		# CREATE VIEW/RULE statements were not pretty-printed before 9.3.
+		# To cope, reduce all whitespace sequences within them to one space.
+		# This must be done on both old and new dumps.
+		$dump = _mash_view_whitespace($dump);
+
+		# _mash_view_whitespace doesn't handle multi-command rules;
+		# rather than trying to fix that, just hack the exceptions manually.
+
+		my $prefix =
+		  "CREATE RULE rtest_sys_del AS ON DELETE TO public.rtest_system DO (DELETE FROM public.rtest_interface WHERE (rtest_interface.sysname = old.sysname);";
+		my $line2 = " DELETE FROM public.rtest_admin";
+		my $line3 = " WHERE (rtest_admin.sysname = old.sysname);";
+		$dump =~
+		  s/(?<=\Q$prefix\E)\Q$line2$line3\E \);/\n$line2\n $line3\n);/mg;
+
+		$prefix =
+		  "CREATE RULE rtest_sys_upd AS ON UPDATE TO public.rtest_system DO (UPDATE public.rtest_interface SET sysname = new.sysname WHERE (rtest_interface.sysname = old.sysname);";
+		$line2 = " UPDATE public.rtest_admin SET sysname = new.sysname";
+		$line3 = " WHERE (rtest_admin.sysname = old.sysname);";
+		$dump =~
+		  s/(?<=\Q$prefix\E)\Q$line2$line3\E \);/\n$line2\n $line3\n);/mg;
+
+		# and there's one place where pre-9.3 uses a different table alias
+		$dump =~ s {^(CREATE\sRULE\srule_and_refint_t3_ins\sAS\s
+			 ON\sINSERT\sTO\spublic\.rule_and_refint_t3\s
+			 WHERE\s\(EXISTS\s\(SELECT\s1\sFROM\spublic\.rule_and_refint_t3)\s
+			 (WHERE\s\(\(\(rule_and_refint_t3)
+			 (\.id3a\s=\snew\.id3a\)\sAND\s\(rule_and_refint_t3)
+			 (\.id3b\s=\snew\.id3b\)\)\sAND\s\(rule_and_refint_t3)}
+		{$1 rule_and_refint_t3_1 $2_1$3_1$4_1}mx;
+
+		# Also fix old use of NATURAL JOIN syntax
+		$dump =~ s {NATURAL JOIN public\.credit_card r}
+			{JOIN public.credit_card r USING (cid)}mg;
+		$dump =~ s {NATURAL JOIN public\.credit_usage r}
+			{JOIN public.credit_usage r USING (cid)}mg;
+	}
+
+	# Suppress blank lines, as some places in pg_dump emit more or fewer.
+	$dump =~ s/\n\n+/\n/g;
+
+	return $dump;
+}
+
+# Internal subroutine to mangle whitespace within view/rule commands.
+# Any consecutive sequence of whitespace is reduced to one space.
+sub _mash_view_whitespace
+{
+	my ($dump) = @_;
+
+	foreach my $leader ('CREATE VIEW', 'CREATE RULE')
+	{
+		my @splitchunks = split $leader, $dump;
+
+		$dump = shift(@splitchunks);
+		foreach my $chunk (@splitchunks)
+		{
+			my @thischunks = split /;/, $chunk, 2;
+			my $stmt = shift(@thischunks);
+
+			# now $stmt is just the body of the CREATE VIEW/RULE
+			$stmt =~ s/\s+/ /sg;
+			# we also need to smash these forms for sub-selects and rules
+			$stmt =~ s/\( SELECT/(SELECT/g;
+			$stmt =~ s/\( INSERT/(INSERT/g;
+			$stmt =~ s/\( UPDATE/(UPDATE/g;
+			$stmt =~ s/\( DELETE/(DELETE/g;
+
+			$dump .= $leader . $stmt . ';' . $thischunks[0];
+		}
+	}
+	return $dump;
+}
+
+=pod
+
+=item adjust_new_dumpfile($old_version, $dump)
+
+Edit a dump output file, taken from the pg_upgrade'd installation
+by current-version C<pg_dumpall -s>, so that it will match the old
+dump output file as adjusted by C<adjust_old_dumpfile>.
+
+Typically this involves deleting data not present in the old installation.
+
+Arguments:
+
+=over
+
+=item C<old_version>: Branch we are upgrading from, represented as a
+PostgreSQL::Version object.
+
+=item C<dump>: Contents of dump file
+
+=back
+
+Returns the modified dump text.
+
+=cut
+
+sub adjust_new_dumpfile
+{
+	my ($old_version, $dump) = @_;
+
+	# use Unix newlines
+	$dump =~ s/\r\n/\n/g;
+
+	# Version comments will certainly not match.
+	$dump =~ s/^-- Dumped from database version.*\n//mg;
+
+	if ($old_version lt '9.3')
+	{
+		# CREATE VIEW/RULE statements were not pretty-printed before 9.3.
+		# To cope, reduce all whitespace sequences within them to one space.
+		# This must be done on both old and new dumps.
+		$dump = _mash_view_whitespace($dump);
+	}
+
+	# Suppress blank lines, as some places in pg_dump emit more or fewer.
+	$dump =~ s/\n\n+/\n/g;
+
+	return $dump;
+}
+
+=pod
+
+=back
+
+=cut
+
+1;