diff --git a/src/backend/catalog/Catalog.pm b/src/backend/catalog/Catalog.pm
index 823e09aa56..0b057a8f5a 100644
--- a/src/backend/catalog/Catalog.pm
+++ b/src/backend/catalog/Catalog.pm
@@ -384,4 +384,55 @@ sub FindDefinedSymbolFromData
 	die "no definition found for $symbol\n";
 }
 
+# Extract an array of all the OIDs assigned in the specified catalog headers
+# and their associated data files (if any).
+sub FindAllOidsFromHeaders
+{
+	my @input_files = @_;
+
+	my @oids = ();
+
+	foreach my $header (@input_files)
+	{
+		$header =~ /(.+)\.h$/
+		  or die "Input files need to be header files.\n";
+		my $datfile = "$1.dat";
+
+		my $catalog = Catalog::ParseHeader($header);
+
+		# We ignore the pg_class OID and rowtype OID of bootstrap catalogs,
+		# as those are expected to appear in the initial data for pg_class
+		# and pg_type.  For regular catalogs, include these OIDs.
+		if (!$catalog->{bootstrap})
+		{
+			push @oids, $catalog->{relation_oid}
+			  if ($catalog->{relation_oid});
+			push @oids, $catalog->{rowtype_oid} if ($catalog->{rowtype_oid});
+		}
+
+		# Not all catalogs have a data file.
+		if (-e $datfile)
+		{
+			my $catdata =
+			  Catalog::ParseData($datfile, $catalog->{columns}, 0);
+
+			foreach my $row (@$catdata)
+			{
+				push @oids, $row->{oid} if defined $row->{oid};
+			}
+		}
+
+		foreach my $toast (@{ $catalog->{toasting} })
+		{
+			push @oids, $toast->{toast_oid}, $toast->{toast_index_oid};
+		}
+		foreach my $index (@{ $catalog->{indexing} })
+		{
+			push @oids, $index->{index_oid};
+		}
+	}
+
+	return \@oids;
+}
+
 1;
diff --git a/src/include/catalog/duplicate_oids b/src/include/catalog/duplicate_oids
index db9b370c2f..0d7aa15559 100755
--- a/src/include/catalog/duplicate_oids
+++ b/src/include/catalog/duplicate_oids
@@ -1,27 +1,20 @@
 #!/usr/bin/perl
 
+use lib '../../backend/catalog/';
+use Catalog;
+
 use strict;
 use warnings;
 
-BEGIN
-{
-	@ARGV = (glob("pg_*.h"), glob("pg_*.dat"), qw(indexing.h toasting.h));
-}
+my @input_files = (glob("pg_*.h"), qw(indexing.h toasting.h));
+
+my $oids = Catalog::FindAllOidsFromHeaders(@input_files);
 
 my %oidcounts;
 
-while (<>)
+foreach my $oid (@{$oids})
 {
-	next if /^CATALOG\(.*BKI_BOOTSTRAP/;
-	next
-	  unless /\boid *=> *'(\d+)'/
-	  || /^CATALOG\([^,]*, *(\d+).*BKI_ROWTYPE_OID\((\d+),/
-	  || /^CATALOG\([^,]*, *(\d+)/
-	  || /^DECLARE_INDEX\([^,]*, *(\d+)/
-	  || /^DECLARE_UNIQUE_INDEX\([^,]*, *(\d+)/
-	  || /^DECLARE_TOAST\([^,]*, *(\d+), *(\d+)/;
-	$oidcounts{$1}++;
-	$oidcounts{$2}++ if $2;
+	$oidcounts{$oid}++;
 }
 
 my $found = 0;
diff --git a/src/include/catalog/unused_oids b/src/include/catalog/unused_oids
index f71222d50d..a727225abc 100755
--- a/src/include/catalog/unused_oids
+++ b/src/include/catalog/unused_oids
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/perl
 #
 # unused_oids
 #
@@ -15,43 +15,40 @@
 #
 #	run this script in src/include/catalog.
 #
+use lib '../../backend/catalog/';
+use Catalog;
 
+use strict;
+use warnings;
 
-AWK="awk"
+my @input_files = (glob("pg_*.h"), qw(indexing.h toasting.h));
 
-# Get FirstBootstrapObjectId from access/transam.h
-FIRSTOBJECTID=`grep '#define[ 	]*FirstBootstrapObjectId' ../access/transam.h | $AWK '{ print $3 }'`
-export FIRSTOBJECTID
+my $oids = Catalog::FindAllOidsFromHeaders(@input_files);
 
-# this part (down to the uniq step) should match the duplicate_oids script
-# note: we exclude BKI_BOOTSTRAP relations since they are expected to have
-# matching data entries in pg_class.dat and pg_type.dat
+# Also push FirstBootstrapObjectId to serve as a terminator for the last gap.
+my $FirstBootstrapObjectId =
+  Catalog::FindDefinedSymbol('access/transam.h', [".."],
+	'FirstBootstrapObjectId');
+push @{$oids}, $FirstBootstrapObjectId;
 
-cat pg_*.h pg_*.dat toasting.h indexing.h |
-egrep -v -e '^CATALOG\(.*BKI_BOOTSTRAP' | \
-sed -n	-e 's/.*\boid *=> *'\''\([0-9][0-9]*\)'\''.*$/\1/p' \
-	-e 's/^CATALOG([^,]*, *\([0-9][0-9]*\).*BKI_ROWTYPE_OID(\([0-9][0-9]*\),.*$/\1,\2/p' \
-	-e 's/^CATALOG([^,]*, *\([0-9][0-9]*\).*$/\1/p' \
-	-e 's/^DECLARE_INDEX([^,]*, *\([0-9][0-9]*\).*$/\1/p' \
-	-e 's/^DECLARE_UNIQUE_INDEX([^,]*, *\([0-9][0-9]*\).*$/\1/p' \
-	-e 's/^DECLARE_TOAST([^,]*, *\([0-9][0-9]*\), *\([0-9][0-9]*\).*$/\1,\2/p' | \
-tr ',' '\n' | \
-sort -n | \
-uniq | \
-$AWK '
-BEGIN {
-	last = 0;
-}
-/^[0-9]/ {
-	if ($1 > last + 1) {
-		if ($1 > last + 2) {
-			print last + 1, "-", $1 - 1;
-		} else {
-			print last + 1;
+my $prev_oid = 0;
+foreach my $oid (sort { $a <=> $b } @{$oids})
+{
+	if ($oid > $prev_oid + 1)
+	{
+		if ($oid > $prev_oid + 2)
+		{
+			printf "%d - %d\n", $prev_oid + 1, $oid - 1;
+		}
+		else
+		{
+			printf "%d\n", $prev_oid + 1;
 		}
 	}
-	last = $1;
+	elsif ($oid == $prev_oid)
+	{
+		print "Duplicate oid detected: $oid\n";
+		exit 1;
+	}
+	$prev_oid = $oid;
 }
-END {
-	print last + 1, "-", ENVIRON["FIRSTOBJECTID"]-1;
-}'