diff --git a/core/lib/Drupal/Core/Database/Query/Select.php b/core/lib/Drupal/Core/Database/Query/Select.php
index 2d3159c..251fb59 100644
--- a/core/lib/Drupal/Core/Database/Query/Select.php
+++ b/core/lib/Drupal/Core/Database/Query/Select.php
@@ -121,6 +121,20 @@ class Select extends Query implements SelectInterface {
    */
   protected $forUpdate = FALSE;
 
+  /**
+   * Constructor
+   *
+   * Creates a new select query.
+   *
+   * @param string $table
+   *   The base table for the select query
+   * @param string $alias
+   *   The alias for the table
+   * @param Drupal\Core\Database\Connection $connection
+   *   Database connection through which the table will be accessed
+   * @param array $options
+   *   Query options
+   */
   public function __construct($table, $alias = NULL, Connection $connection, $options = array()) {
     $options['return'] = Database::RETURN_STATEMENT;
     parent::__construct($connection, $options);
@@ -129,45 +143,68 @@ class Select extends Query implements SelectInterface {
     $this->addJoin(NULL, $table, $alias);
   }
 
-  /* Implementations of Drupal\Core\Database\Query\AlterableInterface. */
-
+    /**
+     * Implements Drupal\Core\Database\Query\AlterableInterface::addTag().
+     */
   public function addTag($tag) {
     $this->alterTags[$tag] = 1;
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::hasTag().
+   */
   public function hasTag($tag) {
     return isset($this->alterTags[$tag]);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::hasAllTags().
+   */
   public function hasAllTags() {
     return !(boolean)array_diff(func_get_args(), array_keys($this->alterTags));
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::hasAnyTag().
+   */
   public function hasAnyTag() {
     return (boolean)array_intersect(func_get_args(), array_keys($this->alterTags));
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::addMetaData().
+   */
   public function addMetaData($key, $object) {
     $this->alterMetaData[$key] = $object;
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::getMetaData().
+   */
   public function getMetaData($key) {
     return isset($this->alterMetaData[$key]) ? $this->alterMetaData[$key] : NULL;
   }
 
-  /* Implementations of Drupal\Core\Database\Query\ConditionInterface for the WHERE clause. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::condition().
+   */
   public function condition($field, $value = NULL, $operator = NULL) {
     $this->where->condition($field, $value, $operator);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::conditions().
+   */
   public function &conditions() {
     return $this->where->conditions();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::arguments().
+   */
   public function arguments() {
     if (!$this->compiled()) {
       return NULL;
@@ -200,31 +237,49 @@ class Select extends Query implements SelectInterface {
     return $args;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::where().
+   */
   public function where($snippet, $args = array()) {
     $this->where->where($snippet, $args);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::isNull().
+   */
   public function isNull($field) {
     $this->where->isNull($field);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::isNull().
+   */
   public function isNotNull($field) {
     $this->where->isNotNull($field);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::exists().
+   */
   public function exists(SelectInterface $select) {
     $this->where->exists($select);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::notExists().
+   */
   public function notExists(SelectInterface $select) {
     $this->where->notExists($select);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::compile().
+   */
   public function compile(Connection $connection, PlaceholderInterface $queryPlaceholder) {
     $this->where->compile($connection, $queryPlaceholder);
     $this->having->compile($connection, $queryPlaceholder);
@@ -242,6 +297,9 @@ class Select extends Query implements SelectInterface {
     }
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::compiled().
+   */
   public function compiled() {
     if (!$this->where->compiled() || !$this->having->compiled()) {
       return FALSE;
@@ -265,32 +323,51 @@ class Select extends Query implements SelectInterface {
     return TRUE;
   }
 
-  /* Implementations of Drupal\Core\Database\Query\ConditionInterface for the HAVING clause. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::condition() for
+   * the HAVING clause.
+   */
   public function havingCondition($field, $value = NULL, $operator = NULL) {
     $this->having->condition($field, $value, $operator);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::conditions() for
+   * the HAVING clause.
+   */
   public function &havingConditions() {
     return $this->having->conditions();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::arguments() for
+   * the HAVING clause.
+   */
   public function havingArguments() {
     return $this->having->arguments();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::where() for the
+   * HAVING clause.
+   */
   public function having($snippet, $args = array()) {
     $this->having->where($snippet, $args);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::compile() for the
+   * HAVING clause.
+   */
   public function havingCompile(Connection $connection) {
     return $this->having->compile($connection, $this);
   }
 
-  /* Implementations of Drupal\Core\Database\Query\ExtendableInterface. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\ExtendableInterface::extend().
+   */
   public function extend($extender_name) {
     $override_class = $extender_name . '_' . $this->connection->driver();
     if (class_exists($override_class)) {
@@ -299,26 +376,45 @@ class Select extends Query implements SelectInterface {
     return new $extender_name($this, $this->connection);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::isNull() for the
+   * HAVING clause.
+   */
   public function havingIsNull($field) {
     $this->having->isNull($field);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::isNotNull() for
+   * the HAVING clause.
+   */
   public function havingIsNotNull($field) {
     $this->having->isNotNull($field);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::exists() for the
+   * HAVING clause.
+   */
   public function havingExists(SelectInterface $select) {
     $this->having->exists($select);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::notExists() for
+   * the HAVING clause.
+   */
   public function havingNotExists(SelectInterface $select) {
     $this->having->notExists($select);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::forUpdate().
+   */
   public function forUpdate($set = TRUE) {
     if (isset($set)) {
       $this->forUpdate = $set;
@@ -326,32 +422,51 @@ class Select extends Query implements SelectInterface {
     return $this;
   }
 
-  /* Alter accessors to expose the query data to alter hooks. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getFields().
+   */
   public function &getFields() {
     return $this->fields;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getExpressions().
+   */
   public function &getExpressions() {
     return $this->expressions;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getOrderBy().
+   */
   public function &getOrderBy() {
     return $this->order;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getGroupBy().
+   */
   public function &getGroupBy() {
     return $this->group;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getTables().
+   */
   public function &getTables() {
     return $this->tables;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getUnion().
+   */
   public function &getUnion() {
     return $this->union;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getArguments().
+   */
   public function getArguments(PlaceholderInterface $queryPlaceholder = NULL) {
     if (!isset($queryPlaceholder)) {
       $queryPlaceholder = $this;
@@ -361,17 +476,14 @@ class Select extends Query implements SelectInterface {
   }
 
   /**
-   * Indicates if preExecute() has already been called on that object.
+   * Implements Drupal\Core\Database\Query\SelectInterface::isPrepared().
    */
   public function isPrepared() {
     return $this->prepared;
   }
 
   /**
-   * Generic preparation and validation for a SELECT query.
-   *
-   * @return
-   *   TRUE if the validation was successful, FALSE if not.
+   * Implements Drupal\Core\Database\Query\SelectInterface::preExecute().
    */
   public function preExecute(SelectInterface $query = NULL) {
     // If no query object is passed in, use $this.
@@ -409,6 +521,9 @@ class Select extends Query implements SelectInterface {
     return $this->prepared;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::execute().
+   */
   public function execute() {
     // If validation fails, simply return NULL.
     // Note that validation routines in preExecute() may throw exceptions instead.
@@ -420,11 +535,17 @@ class Select extends Query implements SelectInterface {
     return $this->connection->query((string) $this, $args, $this->queryOptions);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::distinct().
+   */
   public function distinct($distinct = TRUE) {
     $this->distinct = $distinct;
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::addField().
+   */
   public function addField($table_alias, $field, $alias = NULL) {
     // If no alias is specified, first try the field name itself.
     if (empty($alias)) {
@@ -453,6 +574,9 @@ class Select extends Query implements SelectInterface {
     return $alias;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::fields().
+   */
   public function fields($table_alias, array $fields = array()) {
 
     if ($fields) {
@@ -469,6 +593,9 @@ class Select extends Query implements SelectInterface {
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::addExpression().
+   */
   public function addExpression($expression, $alias = NULL, $arguments = array()) {
     if (empty($alias)) {
       $alias = 'expression';
@@ -490,22 +617,37 @@ class Select extends Query implements SelectInterface {
     return $alias;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::join().
+   */
   public function join($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->addJoin('INNER', $table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::join().
+   */
   public function innerJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->addJoin('INNER', $table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::leftJoin().
+   */
   public function leftJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->addJoin('LEFT OUTER', $table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::rightJoin().
+   */
   public function rightJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->addJoin('RIGHT OUTER', $table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::addJoin().
+   */
   public function addJoin($type, $table, $alias = NULL, $condition = NULL, $arguments = array()) {
 
     if (empty($alias)) {
@@ -539,22 +681,34 @@ class Select extends Query implements SelectInterface {
     return $alias;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::orderBy().
+   */
   public function orderBy($field, $direction = 'ASC') {
     $this->order[$field] = $direction;
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::orderRandom().
+   */
   public function orderRandom() {
     $alias = $this->addExpression('RAND()', 'random_field');
     $this->orderBy($alias);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::range().
+   */
   public function range($start = NULL, $length = NULL) {
     $this->range = func_num_args() ? array('start' => $start, 'length' => $length) : array();
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::union().
+   */
   public function union(SelectInterface $query, $type = '') {
     // Handle UNION aliasing.
     switch ($type) {
@@ -577,11 +731,17 @@ class Select extends Query implements SelectInterface {
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::groupBy().
+   */
   public function groupBy($field) {
     $this->group[$field] = $field;
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::countQuery().
+   */
   public function countQuery() {
     // Create our new query object that we will mutate into a count query.
     $count = clone($this);
@@ -636,6 +796,12 @@ class Select extends Query implements SelectInterface {
     return $query;
   }
 
+  /**
+   * Return the query as a string.
+   *
+   * @return string
+   *  The compiled query
+   */
   public function __toString() {
     // For convenience, we compile the query ourselves if the caller forgot
     // to do it. This allows constructs like "(string) $query" to work. When
@@ -751,6 +917,11 @@ class Select extends Query implements SelectInterface {
     return $query;
   }
 
+  /**
+   * Clone the Select query object.
+   *
+   * Clones the query being sure to clone all object properties as well.
+   */
   public function __clone() {
     // On cloning, also clone the dependent objects. However, we do not
     // want to clone the database connection object as that would duplicate the
diff --git a/core/lib/Drupal/Core/Database/Query/SelectExtender.php b/core/lib/Drupal/Core/Database/Query/SelectExtender.php
index 2f27d1b..71fc5d3 100644
--- a/core/lib/Drupal/Core/Database/Query/SelectExtender.php
+++ b/core/lib/Drupal/Core/Database/Query/SelectExtender.php
@@ -58,127 +58,203 @@ class SelectExtender implements SelectInterface {
     return $this->placeholder++;
   }
 
-  /* Implementations of Drupal\Core\Database\Query\AlterableInterface. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::addTag().
+   */
   public function addTag($tag) {
     $this->query->addTag($tag);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::hasTag().
+   */
   public function hasTag($tag) {
     return $this->query->hasTag($tag);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::hasAllTags().
+   */
   public function hasAllTags() {
     return call_user_func_array(array($this->query, 'hasAllTags'), func_get_args());
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::hasAnyTag().
+   */
   public function hasAnyTag() {
     return call_user_func_array(array($this->query, 'hasAnyTags'), func_get_args());
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::addMetaData().
+   */
   public function addMetaData($key, $object) {
     $this->query->addMetaData($key, $object);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\AlterableInterface::getMetaData().
+   */
   public function getMetaData($key) {
     return $this->query->getMetaData($key);
   }
 
-  /* Implementations of Drupal\Core\Database\Query\ConditionInterface for the WHERE clause. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::condition().
+   */
   public function condition($field, $value = NULL, $operator = NULL) {
     $this->query->condition($field, $value, $operator);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::conditions().
+   */
   public function &conditions() {
     return $this->query->conditions();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::arguments().
+   */
   public function arguments() {
     return $this->query->arguments();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::where().
+   */
   public function where($snippet, $args = array()) {
     $this->query->where($snippet, $args);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::compile().
+   */
   public function compile(Connection $connection, PlaceholderInterface $queryPlaceholder) {
     return $this->query->compile($connection, $queryPlaceholder);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::compiled().
+   */
   public function compiled() {
     return $this->query->compiled();
   }
 
-  /* Implementations of Drupal\Core\Database\Query\ConditionInterface for the HAVING clause. */
-
+  /**
+   * Returns the Drupal\Core\Database\Query\ConditionInterface::condition() for
+   * the HAVING clause.
+   */
   public function havingCondition($field, $value = NULL, $operator = '=') {
     $this->query->havingCondition($field, $value, $operator);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::conditions() for
+   * the HAVING clause.
+   */
   public function &havingConditions() {
     return $this->query->havingConditions();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::arguments() for
+   * the HAVING clause.
+   */
   public function havingArguments() {
     return $this->query->havingArguments();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::where() for
+   * the HAVING clause.
+   */
   public function having($snippet, $args = array()) {
     $this->query->having($snippet, $args);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::compile() for
+   * the HAVING clause.
+   */
   public function havingCompile(Connection $connection) {
     return $this->query->havingCompile($connection);
   }
 
-  /* Implementations of Drupal\Core\Database\Query\ExtendableInterface. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\ExtendableInterface::extend().
+   */
   public function extend($extender_name) {
     $class = $this->connection->getDriverClass($extender_name);
     return new $class($this, $this->connection);
   }
 
-  /* Alter accessors to expose the query data to alter hooks. */
-
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getFields().
+   */
   public function &getFields() {
     return $this->query->getFields();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getExpressions().
+   */
   public function &getExpressions() {
     return $this->query->getExpressions();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getOrderBy().
+   */
   public function &getOrderBy() {
     return $this->query->getOrderBy();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getGroupBy().
+   */
   public function &getGroupBy() {
     return $this->query->getGroupBy();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getTables().
+   */
   public function &getTables() {
     return $this->query->getTables();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getUnion().
+   */
   public function &getUnion() {
     return $this->query->getUnion();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::getArguments().
+   */
   public function getArguments(PlaceholderInterface $queryPlaceholder = NULL) {
     return $this->query->getArguments($queryPlaceholder);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::isPrepared().
+   */
   public function isPrepared() {
     return $this->query->isPrepared();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::preExecute().
+   */
   public function preExecute(SelectInterface $query = NULL) {
     // If no query object is passed in, use $this.
     if (!isset($query)) {
@@ -188,6 +264,9 @@ class SelectExtender implements SelectInterface {
     return $this->query->preExecute($query);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::execute().
+   */
   public function execute() {
     // By calling preExecute() here, we force it to preprocess the extender
     // object rather than just the base query object.  That means
@@ -199,102 +278,173 @@ class SelectExtender implements SelectInterface {
     return $this->query->execute();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::distinct().
+   */
   public function distinct($distinct = TRUE) {
     $this->query->distinct($distinct);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::addField().
+   */
   public function addField($table_alias, $field, $alias = NULL) {
     return $this->query->addField($table_alias, $field, $alias);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::fields().
+   */
   public function fields($table_alias, array $fields = array()) {
     $this->query->fields($table_alias, $fields);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::addExpression().
+   */
   public function addExpression($expression, $alias = NULL, $arguments = array()) {
     return $this->query->addExpression($expression, $alias, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::join().
+   */
   public function join($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->query->join($table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::innerJoin().
+   */
   public function innerJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->query->innerJoin($table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::leftJoin().
+   */
   public function leftJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->query->leftJoin($table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::rightJoin().
+   */
   public function rightJoin($table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->query->rightJoin($table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::addJoin().
+   */
   public function addJoin($type, $table, $alias = NULL, $condition = NULL, $arguments = array()) {
     return $this->query->addJoin($type, $table, $alias, $condition, $arguments);
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::orderBy().
+   */
   public function orderBy($field, $direction = 'ASC') {
     $this->query->orderBy($field, $direction);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::orderRandom().
+   */
   public function orderRandom() {
     $this->query->orderRandom();
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::range().
+   */
   public function range($start = NULL, $length = NULL) {
     $this->query->range($start, $length);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::union().
+   */
   public function union(SelectInterface $query, $type = '') {
     $this->query->union($query, $type);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::groupBy().
+   */
   public function groupBy($field) {
     $this->query->groupBy($field);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::forUpdate().
+   */
   public function forUpdate($set = TRUE) {
     $this->query->forUpdate($set);
     return $this;
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\SelectInterface::countQuery().
+   */
   public function countQuery() {
     return $this->query->countQuery();
   }
 
+  /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::isNull().
+   */
   function isNull($field) {
     $this->query->isNull($field);
     return $this;
   }
 
+   /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::isNotNull().
+   */
   function isNotNull($field) {
     $this->query->isNotNull($field);
     return $this;
   }
 
+   /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::exists().
+   */
   public function exists(SelectInterface $select) {
     $this->query->exists($select);
     return $this;
   }
 
+   /**
+   * Implements Drupal\Core\Database\Query\ConditionInterface::notExists().
+   */
   public function notExists(SelectInterface $select) {
     $this->query->notExists($select);
     return $this;
   }
 
+  /**
+   * Return the query as a string.
+   *
+   * @return string
+   *  The compiled query
+   */
   public function __toString() {
     return (string) $this->query;
   }
 
+  /**
+   * Clone the Select query object.
+   *
+   * Clones the query being sure to clone all object properties as well.
+   */
   public function __clone() {
     $this->uniqueIdentifier = uniqid('', TRUE);