diff --git a/src/include/catalog/reformat_dat_file.pl b/src/include/catalog/reformat_dat_file.pl
index ca20fb86da..54ad1b72e5 100755
--- a/src/include/catalog/reformat_dat_file.pl
+++ b/src/include/catalog/reformat_dat_file.pl
@@ -26,8 +26,11 @@ use FindBin;
 use lib "$FindBin::RealBin/../../backend/catalog/";
 use Catalog;
 
-# Names of the metadata fields of a catalog entry.  (line_number is also
-# a metadata field, but we never write it out, so it's not listed here.)
+# Names of the metadata fields of a catalog entry.
+# Note: oid is a normal column from a storage perspective, but it's more
+# important than the rest, so it's listed first among the metadata fields.
+# Note: line_number is also a metadata field, but we never write it out,
+# so it's not listed here.
 my @METADATA =
   ('oid', 'oid_symbol', 'array_type_oid', 'descr', 'autogenerated');
 
@@ -119,7 +122,12 @@ foreach my $catname (@catnames)
 	foreach my $column (@$schema)
 	{
 		my $attname = $column->{name};
-		push @attnames, $attname;
+
+		# We may have ordinary columns at the storage level that we still
+		# want to format as a special value. Exclude these from the column
+		# list so they are not written twice.
+		push @attnames, $attname
+		  if !(grep { $_ eq $attname } @METADATA;
 	}
 
 	# Overwrite .dat files in place, since they are under version control.
@@ -192,8 +200,11 @@ sub strip_default_values
 	foreach my $column (@$schema)
 	{
 		my $attname = $column->{name};
+
+		# It's okay if we have no oid value, since it will be assigned
+		# automatically before bootstrap.
 		die "strip_default_values: $catname.$attname undefined\n"
-		  if !defined $row->{$attname};
+		  if !defined $row->{$attname} and $attname ne 'oid';
 
 		if (defined $column->{default}
 			and ($row->{$attname} eq $column->{default}))