json - mysql cant save my big decimal number -

i have number 34.59704151614417

and put datatype on decimal(16,14) has saved 34.59704151614400

it means mysql save 12 digit decimal array

array (

                [geometry] => array                     (                         [type] => polygon                         [coordinates] => array                             (                                 [0] => array                                     (                                         [0] => array                                             (                                                 [0] => 32.34375                                                 [1] => 48.690960390925                                             )                                          [1] => array                                             (                                                 [0] => 16.875                                                 [1] => 34.597041516144                                             )                                          [2] => array                                             (                                                 [0] => 43.2421875                                                 [1] => 31.653381399664                                             )                                          [3] => array                                             (                                                 [0] => 64.3359375                                                 [1] => 40.97989806962                                             )                                          [4] => array                                             (                                                 [0] => 32.34375                                                 [1] => 48.690960390925                                             )                                      )                              )                      )              ) 

i understand after json_decode of array reduce it's digit 12 number

set precision directive:

ini_set('precision', 16); 

it 14 , that's why decimals reduced. check this link more information