Verify roundtrip dump/restore of regression database

Add a test to pg_upgrade's test suite that verifies that
dump-restore-dump of regression database produces equivalent output to
dumping it directly.  This was already being tested by running
pg_upgrade itself, but non-binary-upgrade mode was not being covered.

The regression database has accrued, over time, a sufficient collection
of interesting objects to ensure good coverage, but there hasn't been a
concerted effort to be completely exhaustive, so it is likely still
possible to have more.

This'd belong more naturally in the pg_dump test suite, but we chose to
put it in src/bin/pg_upgrade/t/002_pg_upgrade.pl because we need a run
of the regression tests which is already done here, so this has less
total test runtime impact.  Also, experiments have shown that using
parallel dump/restore is slightly faster, so we use --format=directory -j2.

This test has already reported pg_dump bugs, as fixed in fd41ba93e4,
74563f6b90, d611f8b158, 4694aedf63.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://www.postgresql.org/message-id/CAExHW5uF5V=Cjecx3_Z=7xfh4rg2Wf61PT+hfquzjBqouRzQJQ@mail.gmail.com

src/test/perl/Makefile

@@ -25,6 +25,7 @@ install: all installdirs
 	$(INSTALL_DATA) $(srcdir)/PostgreSQL/Test/Kerberos.pm '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/Kerberos.pm'
 	$(INSTALL_DATA) $(srcdir)/PostgreSQL/Test/Cluster.pm '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/Cluster.pm'
 	$(INSTALL_DATA) $(srcdir)/PostgreSQL/Test/BackgroundPsql.pm '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/BackgroundPsql.pm'
+	$(INSTALL_DATA) $(srcdir)/PostgreSQL/Test/AdjustDump.pm '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/AdjustDump.pm'
 	$(INSTALL_DATA) $(srcdir)/PostgreSQL/Test/AdjustUpgrade.pm '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/AdjustUpgrade.pm'
 	$(INSTALL_DATA) $(srcdir)/PostgreSQL/Version.pm '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Version.pm'
 
@@ -35,6 +36,7 @@ uninstall:
 	rm -f '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/Kerberos.pm'
 	rm -f '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/Cluster.pm'
 	rm -f '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/BackgroundPsql.pm'
+	rm -f '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/AdjustDump.pm'
 	rm -f '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Test/AdjustUpgrade.pm'
 	rm -f '$(DESTDIR)$(pgxsdir)/$(subdir)/PostgreSQL/Version.pm'
 

src/test/perl/PostgreSQL/Test/AdjustDump.pm

@@ -0,0 +1,157 @@
+# Copyright (c) 2024-2025, PostgreSQL Global Development Group
+
+=pod
+
+=head1 NAME
+
+PostgreSQL::Test::AdjustDump - helper module for dump/restore tests
+
+=head1 SYNOPSIS
+
+  use PostgreSQL::Test::AdjustDump;
+
+  # Adjust contents of dump output file so that dump output from original
+  # regression database and that from the restored regression database match
+  $dump = adjust_regress_dumpfile($dump, $adjust_child_columns);
+
+=head1 DESCRIPTION
+
+C<PostgreSQL::Test::AdjustDump> encapsulates various hacks needed to
+compare the results of dump/restore tests.
+
+=cut
+
+package PostgreSQL::Test::AdjustDump;
+
+use strict;
+use warnings FATAL => 'all';
+
+use Exporter 'import';
+use Test::More;
+
+our @EXPORT = qw(
+  adjust_regress_dumpfile
+);
+
+=pod
+
+=head1 ROUTINES
+
+=over
+
+=item $dump = adjust_regress_dumpfile($dump, $adjust_child_columns)
+
+Edit a dump output file, taken from the source regression database,
+to remove the known differences to a dump taken after restoring the
+same database.
+
+Arguments:
+
+=over
+
+=item C<dump>: Contents of dump file
+
+=item C<adjust_child_columns>: 1 indicates that the given dump file requires
+adjusting columns in the child tables; usually when the dump is from original
+database. 0 indicates no such adjustment is needed; usually when the dump is
+from restored database.
+
+=back
+
+Returns the adjusted dump text.
+
+Adjustments Applied:
+
+=over
+
+=item Column reordering on child table creation
+
+This rearranges the column declarations in the C<CREATE TABLE... INHERITS>
+statements in the dump file from original database so that they match those
+from the restored database.
+
+Only executed if C<adjust_child_columns> is true.
+
+Context: some regression tests purposefully create child tables in such a way
+that the order of their inherited columns differ from column orders of their
+respective parents.  In the restored database, however, the order of their
+inherited columns are same as that of their respective parents. Thus the column
+orders of these child tables in the original database and those in the restored
+database differ, causing difference in the dump outputs. See
+C<MergeAttributes()> and C<dumpTableSchema()> for details.
+
+=item Removal of problematic C<COPY> statements
+
+Remove COPY statements to abnormal children tables.
+
+Context: This difference is caused because of columns that are added to parent
+tables that already have children; because recreating the children tables puts
+the columns from the parent ahead of columns declared locally in children,
+these extra columns are in earlier position compared to the original database.
+Reordering columns on the entire C<COPY> data is impractical, so we just remove
+them.
+
+=item Newline adjustment
+
+Windows-style newlines are changed to Unix-style.  Empty lines are trimmed.
+
+=back
+
+=cut
+
+sub adjust_regress_dumpfile
+{
+	my ($dump, $adjust_child_columns) = @_;
+
+	# use Unix newlines
+	$dump =~ s/\r\n/\n/g;
+
+	# Adjust the CREATE TABLE ... INHERITS statements.
+	if ($adjust_child_columns)
+	{
+		$dump =~ s/(^CREATE\sTABLE\sgenerated_stored_tests\.gtestxx_4\s\()
+		(\n\s+b\sinteger),
+		(\n\s+a\sinteger\sNOT\sNULL)/$1$3,$2/mgx;
+
+		$dump =~ s/(^CREATE\sTABLE\sgenerated_virtual_tests\.gtestxx_4\s\()
+		(\n\s+b\sinteger),
+		(\n\s+a\sinteger\sNOT\sNULL)/$1$3,$2/mgx;
+
+		$dump =~ s/(^CREATE\sTABLE\spublic\.test_type_diff2_c1\s\()
+		(\n\s+int_four\sbigint),
+		(\n\s+int_eight\sbigint),
+		(\n\s+int_two\ssmallint)/$1$4,$2,$3/mgx;
+
+		$dump =~ s/(^CREATE\sTABLE\spublic\.test_type_diff2_c2\s\()
+		(\n\s+int_eight\sbigint),
+		(\n\s+int_two\ssmallint),
+		(\n\s+int_four\sbigint)/$1$3,$4,$2/mgx;
+	}
+
+	# Remove COPY statements with differing column order
+	for my $table (
+		'public\.b_star', 'public\.c_star',
+		'public\.cc2', 'public\.d_star',
+		'public\.e_star', 'public\.f_star',
+		'public\.renamecolumnanother', 'public\.renamecolumnchild',
+		'public\.test_type_diff2_c1', 'public\.test_type_diff2_c2',
+		'public\.test_type_diff_c')
+	{
+		# This multiline pattern matches the whole COPY, up to the
+		# terminating "\."
+		$dump =~ s/^COPY $table \(.+?^\\\.$//sm;
+	}
+
+	# 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;

src/test/perl/meson.build

@@ -13,5 +13,6 @@ install_data(
   'PostgreSQL/Test/Kerberos.pm',
   'PostgreSQL/Test/Cluster.pm',
   'PostgreSQL/Test/BackgroundPsql.pm',
+  'PostgreSQL/Test/AdjustDump.pm',
   'PostgreSQL/Test/AdjustUpgrade.pm',
   install_dir: dir_pgxs / 'src/test/perl/PostgreSQL/Test')