Connection::open

public static Connection::open(array &$connection_options = array())

public static function open(array &$connection_options = array()) {
  // Default to TCP connection on port 5432.
  if (empty($connection_options['port'])) {
    $connection_options['port'] = 5432;
  }

  // PostgreSQL in trust mode doesn't require a password to be supplied.
  if (empty($connection_options['password'])) {
    $connection_options['password'] = NULL;
  }
  // If the password contains a backslash it is treated as an escape character
  // http://bugs.php.net/bug.php?id=53217
  // so backslashes in the password need to be doubled up.
  // The bug was reported against pdo_pgsql 1.0.2, backslashes in passwords
  // will break on this doubling up when the bug is fixed, so check the version
  //elseif (phpversion('pdo_pgsql') < 'version_this_was_fixed_in') {
  else {
    $connection_options['password'] = str_replace('\\', '\\\\', $connection_options['password']);
  }

  $connection_options['database'] = (!empty($connection_options['database']) ? $connection_options['database'] : 'template1');
  $dsn = 'pgsql:host=' . $connection_options['host'] . ' dbname=' . $connection_options['database'] . ' port=' . $connection_options['port'];

  // Allow PDO options to be overridden.
  $connection_options += array(
    'pdo' => array(),
  );
  $connection_options['pdo'] += array(
    \PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
    // Prepared statements are most effective for performance when queries
    // are recycled (used several times). However, if they are not re-used,
    // prepared statements become inefficient. Since most of Drupal's
    // prepared queries are not re-used, it should be faster to emulate
    // the preparation than to actually ready statements for re-use. If in
    // doubt, reset to FALSE and measure performance.
    \PDO::ATTR_EMULATE_PREPARES => TRUE,
    // Convert numeric values to strings when fetching.
    \PDO::ATTR_STRINGIFY_FETCHES => TRUE,
  );
  $pdo = new \PDO($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);

  return $pdo;
}