diff --git a/core/lib/Drupal/Core/Database/Connection.php b/core/lib/Drupal/Core/Database/Connection.php
index 6eed7f8..6716e89 100755
--- a/core/lib/Drupal/Core/Database/Connection.php
+++ b/core/lib/Drupal/Core/Database/Connection.php
@@ -1297,7 +1297,7 @@ public function commit() {
    * and PostgreSQL can not advance the sequence to be larger than a given
    * value. Or sometimes you just need a unique integer.
    *
-   * @param $existing_id
+   * @param int $existing_id
    *   (optional) The maximum existing ID. After a database import, it might be
    *   that the sequences table is behind, so by passing in the maximum existing
    *   ID, it can be assured that we never issue the same ID.
@@ -1327,7 +1327,7 @@ public function commit() {
    * @return \PDOStatement|false
    *   If the database server successfully prepares the statement, returns a
    *   \PDOStatement object. If the database server cannot successfully prepare
-   *   the statement, returns FALSE or emits \PDOException (depending on error
+   *   the statement, returns FALSE or throws \PDOException (depending on error
    *   handling).
    *
    * @throws \PDOException
diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
index 53cfed6..9a23093 100755
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
@@ -93,11 +93,13 @@ protected function buildTableNameCondition($table_name, $operator = '=', $add_pr
   /**
    * Generate SQL to create a new table from a Drupal schema definition.
    *
-   * @param $name
+   * @param string $name
    *   The name of the table to create.
-   * @param $table
-   *   A Schema API table definition array.
-   * @return
+   * @param array[] $table
+   *   A Schema API table definition array. See @link schemaapi Schema API
+   *   documentation @endlink for more information.
+   *
+   * @return string[]
    *   An array of SQL statements to create the table.
    */
   protected function createTableSql($name, $table) {
@@ -146,12 +148,13 @@ protected function createTableSql($name, $table) {
    * Create an SQL string for a field to be used in table creation or alteration.
    *
    * Before passing a field out of a schema definition into this function it has
-   * to be processed by _db_process_field().
+   * to be processed by processField() method.
    *
    * @param string $name
    *   Name of the field.
-   * @param array $spec
-   *   The field specification, as per the schema data structure format.
+   * @param array[] $spec
+   *   The field specification, as per the schema data structure format. For
+   *   more details, see @link schemaapi Schema API documentation. @endlink
    *
    * @return string
    *   The generated SQL string.
@@ -212,8 +215,12 @@ protected function createFieldSql($name, $spec) {
   /**
    * Set database-engine specific properties for a field.
    *
-   * @param $field
-   *   A field description array, as specified in the schema documentation.
+   * @param array $field
+   *   A field description array, as specified in the schema documentation. For
+   *   more details, see @link schemaapi Schema API documentation. @endlink
+   *
+   * @return array[]
+   *   The field description array with MySQL specific field specifications.
    */
   protected function processField($field) {
 
@@ -287,8 +294,10 @@ public function getFieldTypeMap() {
   /**
    * Generates key and index SQL from a field specification.
    *
-   * @param array $spec
-   *   The field specification.
+   * @param array[] $spec
+   *   The table specification for which to create keys and indexes. For more
+   *   details on the specification, refer to the @link schemaapi Schema API
+   *   documentation. @endlink
    *
    * @return string
    *   The generated SQL snippet.
@@ -380,7 +389,7 @@ protected function shortenIndex(&$index) {
   /**
    * Generates SQL from field definitions.
    *
-   * @param array $fields
+   * @param string[]|array[] $fields
    *   Array of field definitions. Each array value is either:
    *   - A field name (string).
    *   - An array containing the field name and field alias.
@@ -617,9 +626,9 @@ public function prepareComment($comment, $length = NULL) {
   /**
    * Retrieve a table or column comment.
    *
-   * @param $table
+   * @param string $table
    *   The database table to return comments for.
-   * @param $column
+   * @param string $column
    *   (optional) A column in $table to return comments for.
    *
    * @return string
diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
old mode 100644
new mode 100755
index 9ecc1f0..1e209f7
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
@@ -306,7 +306,7 @@ public function mapConditionOperator($operator) {
    * PostgreSQL has built in sequences. We'll use these instead of inserting
    * and updating a sequences table.
    *
-   * @param $existing
+   * @param int $existing
    *   The maximum existing ID makes sure that we never issue the same ID, even
    *   after a database import when it might be that the sequences table is
    *   behind.
diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
index 79aedf8..55523b1 100755
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
@@ -211,8 +211,10 @@ public function queryFieldInformation($table, $field) {
    *
    * @param string $name
    *   The name of the table to create.
-   * @param array $table
-   *   A Schema API table definition array.
+   * @param array[] $table
+   *   A Schema API table definition array. See @link schemaapi Schema API
+   *   documentation @endlink for more information.
+   *
    * @return string[]
    *   An array of SQL statements to create the table.
    */
@@ -267,12 +269,13 @@ protected function createTableSql($name, $table) {
    * alteration.
    *
    * Before passing a field out of a schema definition into this
-   * function it has to be processed by _db_process_field().
+   * function it has to be processed by processField() method.
    *
-   * @param $name
+   * @param string $name
    *   Name of the field.
-   * @param $spec
-   *   The field specification, as per the schema data structure format.
+   * @param array[] $spec
+   *   The field specification, as per the schema data structure format. For
+   *   more details, see @link schemaapi Schema API documentation. @endlink
    *
    * @return string
    *   Generated SQL string.
@@ -408,7 +411,7 @@ function getFieldTypeMap() {
   /**
    * Generates SQL from field definitions.
    *
-   * @param array $fields
+   * @param string[]|array[] $fields
    *   Array of field definitions. Each array value is either:
    *   - A field name (string).
    *   - An array containing the field name and field alias.
@@ -830,7 +833,7 @@ public function changeField($table, $field, $field_new, $spec, $new_keys = array
    *   The table on which the index will be created.
    * @param string $name
    *   An identifying name for this index.
-   * @param array $fields
+   * @param string[]|array[] $fields
    *   Array of field definitions. Each array value is either:
    *   - A field name (string).
    *   - An array containing the field name and field alias.
@@ -849,8 +852,9 @@ protected function _createIndexSql($table, $name, $fields) {
    *
    * @param string $table
    *   The table on which the keys and indexes will be added.
-   * @param array $new_keys
-   *   The field specification.
+   * @param array[] $new_keys
+   *   Schema API specification for the new keys. See @link schemaapi Schema API
+   *   documentation @endlink for more information.
    */
   protected function _createKeys($table, $new_keys) {
     if (isset($new_keys['primary key'])) {
@@ -874,9 +878,9 @@ protected function _createKeys($table, $new_keys) {
   /**
    * Retrieve a table or column comment.
    *
-   * @param $table
+   * @param string $table
    *   The database table to return comments for.
-   * @param $column
+   * @param string $column
    *   (optional) A column in $table to return comments for.
    *
    * @return string
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
old mode 100644
new mode 100755
index 16beaeb..c87b06d
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
@@ -193,8 +193,8 @@ public static function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {
    * @param ...
    *   Variable parameters.
    *
-   * @return mixed|null
-   *   The maximum of the given arguments.
+   * @return mixed
+   *   The maximum of the given arguments. NULL if no arguments specified.
    */
   public static function sqlFunctionGreatest() {
     $args = func_get_args();
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
index 5112036..51760d0 100755
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
@@ -47,10 +47,11 @@ public function fieldExists($table, $column) {
    *
    * @param string $name
    *   The name of the table to create.
-   * @param array $table
-   *   A Schema API table definition array.
+   * @param array[] $table
+   *   A Schema API table definition array. See @link schemaapi Schema API
+   *   documentation @endlink for more information.
    *
-   * @return array
+   * @return string[]
    *   An array of SQL statements to create the table.
    */
   public function createTableSql($name, $table) {
@@ -64,8 +65,9 @@ public function createTableSql($name, $table) {
    *
    * @param string $tablename
    *   The name of the table to create indexes on.
-   * @param array $schema
-   *   A Schema API table definition array.
+   * @param array[] $schema
+   *   A Schema API table definition array. See @link schemaapi Schema API
+   *   documentation @endlink for more details.
    *
    * @return string[]
    *   Array of SQL statements to create the indexes.
@@ -92,7 +94,8 @@ protected function createIndexSql($tablename, $schema) {
    * @param string $tablename
    *   The name of the table to create columns on.
    * @param array $schema
-   *   A Schema API table definition array.
+   *   A Schema API table definition array. See @link schemaapi Schema API
+   *   documentation @endlink for more details.
    *
    * @return string
    *   Generated SQL snippet.
@@ -120,6 +123,14 @@ protected function createColumnsSql($tablename, $schema) {
 
   /**
    * Build the SQL expression for keys.
+   *
+   * @param string[]|array[] $fields
+   *   Array of field definitions. Each array value is either:
+   *   - A field name (string).
+   *   - An array containing the field name and field alias.
+   *
+   * @return string
+   *   The generated SQL snippet.
    */
   protected function createKeySql($fields) {
     $return = array();
@@ -173,10 +184,11 @@ protected function processField($field) {
    * Before passing a field out of a schema definition into this function it has
    * to be processed by db_processField().
    *
-   * @param $name
+   * @param string $name
    *   Name of the field.
-   * @param $spec
-   *   The field specification, as per the schema data structure format.
+   * @param array[] $spec
+   *   The field specification, as per the schema data structure format. For
+   *   more details, see @link schemaapi Schema API documentation. @endlink
    *
    * @return string
    *   Generated SQL string.
@@ -391,11 +403,13 @@ public function addField($table, $field, $specification, $keys_new = array()) {
    *
    * @param string $table
    *   Name of the table to be altered.
-   * @param array $old_schema
-   *   The old schema array for the table.
-   * @param array $new_schema
-   *   The new schema array for the table.
-   * @param array $mapping
+   * @param array[] $old_schema
+   *   The old schema array for the table. See @link schemaapi Schema API
+   *   documentation @endlink for more details.
+   * @param array[] $new_schema
+   *   The new schema array for the table. See @link schemaapi Schema API
+   *   documentation @endlink for more details.
+   * @param string[]|array[] $mapping
    *   An optional mapping between the fields of the old specification and the
    *   fields of the new specification. An associative array, whose keys are
    *   the fields of the new table, and values can take two possible forms:
@@ -457,8 +471,9 @@ protected function alterTable($table, $old_schema, $new_schema, array $mapping =
    * @param string $table
    *   Name of the table.
    *
-   * @return array
-   *   An array representing the schema, from drupal_get_schema().
+   * @return array[]
+   *   An array representing the schema. See @link schemaapi Schema API
+   *   documentation @endlink for more details.
    *
    * @see drupal_get_schema()
    */
@@ -607,9 +622,9 @@ public function changeField($table, $field, $field_new, $spec, $keys_new = array
   /**
    * Utility method: rename columns in an index definition according to a new mapping.
    *
-   * @param $key_definition
+   * @param string[]|array[] $key_definition
    *   The key definition.
-   * @param $mapping
+   * @param string[] $mapping
    *   The new mapping.
    *
    * @return array
diff --git a/core/lib/Drupal/Core/Database/Schema.php b/core/lib/Drupal/Core/Database/Schema.php
old mode 100644
new mode 100755
index b9ff670..f46805f
--- a/core/lib/Drupal/Core/Database/Schema.php
+++ b/core/lib/Drupal/Core/Database/Schema.php
@@ -16,6 +16,9 @@
  */
 abstract class Schema implements PlaceholderInterface {
 
+  /**
+   * @var \Drupal\Core\Database\Connection
+   */
   protected $connection;
 
   /**
@@ -68,13 +71,13 @@ public function nextPlaceholder() {
   /**
    * Get information about the table name and schema from the prefix.
    *
-   * @param
+   * @param string $table
    *   Name of table to look prefix up for. Defaults to 'default' because that's
    *   default key for prefix.
-   * @param $add_prefix
+   * @param bool $add_prefix
    *   Boolean that indicates whether the given table name should be prefixed.
    *
-   * @return
+   * @return array
    *   A keyed array with information about the schema, table name and prefix.
    */
   protected function getPrefixInfo($table = 'default', $add_prefix = TRUE) {
@@ -155,10 +158,10 @@ protected function buildTableNameCondition($table_name, $operator = '=', $add_pr
   /**
    * Check if a table exists.
    *
-   * @param $table
+   * @param string $table
    *   The name of the table in drupal (no prefixing).
    *
-   * @return
+   * @return bool
    *   TRUE if the given table exists, otherwise FALSE.
    */
   public function tableExists($table) {
@@ -520,15 +523,15 @@ public function fieldExists($table, $column) {
    * unless you are converting a field to be type serial. You can use
    * the $keys_new argument in all cases.
    *
-   * @param $table
+   * @param string $table
    *   Name of the table.
-   * @param $field
+   * @param string $field
    *   Name of the field to change.
-   * @param $field_new
+   * @param string $field_new
    *   New name for the field (set to the same as $field if you don't want to change the name).
-   * @param $spec
+   * @param array $spec
    *   The field specification for the new field.
-   * @param $keys_new
+   * @param array[] $keys_new
    *   (optional) Keys and indexes specification to be created on the
    *   table along with changing the field. The format is the same as a
    *   table specification but without the 'fields' element.