adding an "end date" to an existing Date field

I´m having the same issue. Is there any feedback around about it?
Thanks!

This is what I came up with to add an optional end date to an existing date field with data in DB.
It is inspired from field_update_field().

/**
 * Add end date to field_my_field.
 */
function my_module_update_7000() {
  $prior_field = field_info_field('field_my_field');

  // Changes to the current field definition.
  $field = $prior_field;
  $field['settings']['todate'] = 'optional';
  $field['columns']['value2'] = $field['columns']['value'];
  $field['columns']['value2']['views'] = FALSE;
  $field['indexes'] = array(
    'value' => array('value'),
    'value2' => array('value2'),
  );

  // Get new storage details definition.
  $details = (array) module_invoke($field['storage']['module'], 'field_storage_details', $field);
  drupal_alter('field_storage_details', $details, $field);
  $field['storage']['details'] = $details;

  // Update the field_config table.
  $data = $field;
  unset($data['columns'], $data['field_name'], $data['type'], $data['locked'], $data['module'], $data['cardinality'], $data['active'], $data['deleted'], $data['bundles'], $data['data']);
  $field['data'] = $data;
  $primary_key = array('id');
  drupal_write_record('field_config', $field, $primary_key);

  // Update the tables schema.
  $old_schema = _field_sql_storage_schema($prior_field);
  $new_schema = _field_sql_storage_schema($field);
  $schema_changes = drupal_array_diff_assoc_recursive($new_schema, $old_schema);
  if (!empty($schema_changes)) {
    foreach ($schema_changes as $table => $data) {
      foreach ($data['fields'] as $id => $spec) {
        if (!db_field_exists($table, $id)) {
          db_add_field($table, $id, $spec);
        }
      }
      foreach ($data['indexes'] as $id => $spec) {
        if (!db_index_exists($table, $id)) {
          db_add_index($table, $id, $spec);
        }
      }
    }
  }

  // Clear caches.
  field_cache_clear();
}

If your field base is exported in features you also need to change your field_base export (a feature export after running the update might work):

'indexes' => array(
  'value' => array(
    0 => 'value',
  ),
  'value2' => array(
    0 => 'value2',
  ),
),

and

'settings' => array(
  ...
  'todate' => 'optional',
  ...
),

herved, your solution worked perfectly for 3 of my projects where I was about to scratch my head for a very long time. Thanks a lot for your work.

@bernig You're welcome. Glad to hear my solution helped others as well ;)

Hi can you please explain how can i implement this, i can't figure out how do this.

@viswanathsai This is a standard hook_update() to be placed in one of your custom modules .install file.
See also https://api.drupal.org/api/drupal/modules%21system%21system.api.php/func...

You absolute beauty!! Thank you for this!!