diff --git a/lib/backend/abstractbackend.php b/lib/backend/abstractbackend.php
index b0e37645..9461387c 100644
--- a/lib/backend/abstractbackend.php
+++ b/lib/backend/abstractbackend.php
@@ -25,28 +25,30 @@ namespace OCA\Contacts\Backend;
 use OCA\Contacts\VObject\VCard;
 
 /**
- * Subclass this class for address book backends
- *
- * The following methods MUST be implemented:
- * @method array getAddressBooksForUser(array $options = array())
- * @method array|null getAddressBook(string $addressbookid, array $options = array())
- * @method array getContacts(string $addressbookid, array $options = array())
- * @method array|null getContact(string $addressbookid, mixed $id, array $options = array())
- * The following methods MAY be implemented:
- * @method bool hasAddressBook(string $addressbookid)
- * @method bool updateAddressBook(string $addressbookid, array $updates, array $options = array())
- * @method string createAddressBook(array $properties, array $options = array())
- * @method bool deleteAddressBook(string $addressbookid, array $options = array())
- * @method int lastModifiedAddressBook(string $addressbookid)
- * @method array numContacts(string $addressbookid)
- * @method bool updateContact(string $addressbookid, string $id, VCard $contact, array $options = array())
- * @method string createContact(string $addressbookid, VCard $contact, array $properties)
- * @method bool deleteContact(string $addressbookid, string $id, array $options = array())
- * @method int lastModifiedContact(string $addressbookid)
+ * Subclass this class for address book backends.
  */
-
 abstract class AbstractBackend {
 
+	/**
+	* The following methods MUST be implemented:
+	*
+	* @method array getAddressBooksForUser(array $options = array())
+	* @method array|null getAddressBook(string $addressbookid, array $options = array())
+	* @method array getContacts(string $addressbookid, array $options = array())
+	* @method array|null getContact(string $addressbookid, mixed $id, array $options = array())
+	* The following methods MAY be implemented:
+	* @method bool hasAddressBook(string $addressbookid)
+	* @method bool updateAddressBook(string $addressbookid, array $updates, array $options = array())
+	* @method string createAddressBook(array $properties, array $options = array())
+	* @method bool deleteAddressBook(string $addressbookid, array $options = array())
+	* @method int lastModifiedAddressBook(string $addressbookid)
+	* @method array numContacts(string $addressbookid)
+	* @method bool updateContact(string $addressbookid, string $id, VCard $contact, array $options = array())
+	* @method string createContact(string $addressbookid, VCard $contact, array $properties)
+	* @method bool deleteContact(string $addressbookid, string $id, array $options = array())
+	* @method int lastModifiedContact(string $addressbookid)
+	*/
+
 	/**
 	 * The name of the backend.
 	 * @var string
@@ -376,6 +378,7 @@ abstract class AbstractBackend {
 	 * 
 	 * @param string $addressBookId.
 	 * @param string $contactId.
+	 * @throws \BadMethodCallException
 	 * @return string
 	 */
 	protected function combinedKey($addressBookId = null, $contactId = null) {
@@ -446,8 +449,8 @@ abstract class AbstractBackend {
 	 * @param array the preferences, format array('param1' => 'value', 'param2' => 'value')
 	 * @return boolean
 	 */
-	public function setPreferences($addressbookid, array $params) {
-		
+	public function setPreferences($addressBookId, array $params) {
+
 		$key = $this->combinedKey($addressBookId);
 		$key = 'prefs_' . $key;
 
diff --git a/lib/backend/database.php b/lib/backend/database.php
index cbcfeaa4..0e0105d0 100644
--- a/lib/backend/database.php
+++ b/lib/backend/database.php
@@ -28,7 +28,7 @@ use OCA\Contacts\Contact,
 	Sabre\VObject\Reader;
 
 /**
- * Subclass this class for Contacts backends
+ * Subclass this class for Contacts backends.
  */
 
 class Database extends AbstractBackend {
@@ -36,6 +36,30 @@ class Database extends AbstractBackend {
 	public $name = 'local';
 	static private $preparedQueries = array();
 
+	/**
+	 * The cached address books.
+	 * @var array[]
+	 */
+	public $addressbooks;
+
+	/**
+	 * The table that holds the address books.
+	 * @var string
+	 */
+	public $addressBooksTableName;
+
+	/**
+	 * The table that holds the contact vCards.
+	 * @var string
+	 */
+	public $cardsTableName;
+
+	/**
+	 * The table that holds the indexed vCard properties.
+	 * @var string
+	 */
+	public $indexTableName;
+
 	/**
 	* Sets up the backend
 	*
@@ -123,6 +147,7 @@ class Database extends AbstractBackend {
 			if (!$row) {
 				throw new \Exception('Address Book not found', 404);
 			}
+
 			$row['permissions'] = \OCP\PERMISSION_ALL;
 			$row['backend'] = $this->name;
 			$this->addressbooks[$addressbookid] = $row;
@@ -478,31 +503,30 @@ class Database extends AbstractBackend {
 
 		$noCollection = isset($options['noCollection']) ? $options['noCollection'] : false;
 
-		$where_query = '`id` = ?';
+		$whereQuery = '`id` = ?';
 		if (is_array($id)) {
-			$where_query = '';
+			$whereQuery = '';
 			if (isset($id['id'])) {
 				$id = $id['id'];
 			} elseif (isset($id['uri'])) {
-				$where_query = '`uri` = ?';
+				$whereQuery = '`uri` = ?';
 				$id = $id['uri'];
 			} else {
 				throw new \Exception(
 					__METHOD__ . ' If second argument is an array, either \'id\' or \'uri\' has to be set.'
 				);
-				return null;
 			}
 		}
 		$ids = array($id);
 
 		if (!$noCollection) {
-			$where_query .= ' AND `addressbookid` = ?';
+			$whereQuery .= ' AND `addressbookid` = ?';
 			$ids[] = $addressbookid;
 		}
 
 		try {
-			$query =  'SELECT `id`, `uri`, `carddata`, `lastmodified`, `addressbookid` AS `parent`, `fullname` AS `displayname` FROM `'
-				. $this->cardsTableName . '` WHERE ' . $where_query;
+			$query = 'SELECT `id`, `uri`, `carddata`, `lastmodified`, `addressbookid` AS `parent`, `fullname` AS `displayname` FROM `'
+				. $this->cardsTableName . '` WHERE ' . $whereQuery;
 			$stmt = \OCP\DB::prepare($query);
 			$result = $stmt->execute($ids);