how to make drupal use mysqlnd_ms I have installed mysqlnd_ms plugin , created the mysqlnd_ms.json with following configuration.


{
  "myapp": {
    "master": {
      "master_1": {
        "host": "mysql://drupal@1x4.xx6.x.1x9",
        "port":  3306,
        "user": "drupal",
        "password": "password",
        "db": "site2"
      }
    },
    "slave": {
      "slave_0": {
        "host": "mysql://drupal@1xx.1x1.xx9.2x1",
        "port":  3306,
        "user": "drupal",
        "password": "password",
        "db": "site1"
      }
    }
  }
}


its still not splitting the queries! how will drupal work withmynsqlnd. Do i have make edits in setting.php
That extension's operations are transparent to the application, you only need to configure the host that the DB connection is setup with.

From a Drupal point of view, you just need to update the "host" entry for the relevant database in settings.php to match the name of your mysqlnd_ms application. From the looks of your config file that's myapp, so your database connection might look like this:

$databases['default']['default'] = array(
  'driver' =&gt; 'mysql',
  'database' =&gt; 'foo',
  'username' =&gt; 'bar',
  'password' =&gt; 'baz',
  'host' =&gt; 'myapp',
  'prefix' =&gt; '',
);


If that doesn't work, check that the extension is installed, configured, and enabled.