create or replace function get_table_ctime(oid)
returns timestamp language plperlu as $BODY$
use strict;
my $r = spi_exec_query(<<SQL)->{rows}->[ 0 ];
  SELECT
    (SELECT current_setting('data_directory')) as dir,
    (SELECT oid FROM pg_database WHERE datname=current_database()) as db,
    reltablespace as ts,
    relfilenode as file
  FROM pg_class
  WHERE oid=$_[ 0 ]
SQL
my $tsdir = ($r->{ts} ==  0 ) ? 'base' : "pg_tblspc/$r->{ts}";
my $file = "$r->{dir}/$tsdir/$r->{db}/$r->{file}";
my $ctime = (stat $file)[ 10 ] or return undef;
return spi_exec_query(<<SQL)->{rows}->[ 0 ]->{ctime};
  SELECT to_timestamp($ctime) as ctime
SQL
$BODY$;

select get_table_ctime('mytable'::regclass);