@{$db{'key1'}{'key2'}[0][0]} = "one_value";
@{$db{'key1'}{'key2'}[0][1]} = "two_value";
@{$db{'key1'}{'key2'}[1][0]} = "three_value";
@{$db{'key1'}{'key2'}[1][1]} = "four_value";
@{$db{'key1'}{'key2'}[2][0]} = "three_value";
@{$db{'key1'}{'key2'}[2][1]} = "four_value";

print "how many elements does the array have : ",
      scalar (@{$db{'key1'}{'key2'}});
print "\n";
print "popping an element";
pop @{$db{'key1'}{'key2'}};
print "\n";
print "how many elements does the array have now : ",
      scalar (@{$db{'key1'}{'key2'}});