Checks if an index exists in the given table.
$table: The name of the table in drupal (no prefixing).
$name: The name of the index in drupal (no prefixing).
TRUE if the given index exists, otherwise FALSE.
Overrides DatabaseSchema::indexExists
public function indexExists($table, $name) {
// Returns one row for each column in the index. Result is string or FALSE.
// Details at http://dev.mysql.com/doc/refman/5.0/en/show-index.html
$row = $this->connection
->query('SHOW INDEX FROM {' . $table . "} WHERE key_name = '{$name}'")
->fetchAssoc();
return isset($row['Key_name']);
}