while (my $row = $sth->fetch_arrayref()) {
   ...
}

##</code><code>##

my $rows = $sth->fetchall_arrayref();
my $num_rows = @$rows;
foreach my $row (@$rows) {
   ...
}

##</code><code>##

my $rows = $sth->fetchall_arrayref();
my $num_rows = @$rows;

my $sponge = DBI->connect('dbi:Sponge:');
my $sponge_sth = $sponge->prepare(
   $sth->{Statement},
   {
      rows        => $rows,
      NAME        => $sth->{NAME},
      behave_like => $sth,
   }
);

while (my $row = $sponge_sth->fetch_arrayref()) {
   ...
}