Checks if an index exists in the given table.
$table: The name of the table in drupal (no prefixing).
$name: The name of the index in drupal (no prefixing).
TRUE if the given index exists, otherwise FALSE.
Overrides Schema::indexExists
public function indexExists($table, $name) {
$info = $this
->getPrefixInfo($table);
return $this->connection
->query('PRAGMA ' . $info['schema'] . '.index_info(' . $info['table'] . '_' . $name . ')')
->fetchField() != '';
}