CrateDB bulk operations: Add documentation

Author: amotl

docs/connect.rst

@@ -221,6 +221,29 @@ method used.
 |                            | ``PDO::FETCH_OBJ``    |
 +----------------------------+-----------------------+
 
+Bulk operations
+===============
+
+With CrateDB :ref:`crate-reference:http-bulk-ops`, suitable for ``INSERT``,
+``UPDATE``, and ``DELETE`` statements, you can submit multiple records, aka.
+batches, to CrateDB within a single operation. By using this way of communication,
+both the client and the server will not waste resources on building and decoding
+huge SQL statements, and data will also propagate more efficiently between CrateDB
+cluster nodes.
+
+To use this mode, the ``PDOStatement`` offers a corresponding ``bulkMode`` option.
+When creating a statement instance with it, the ``$parameters`` data will be
+obtained as a list of records, like demonstrated in the example below.
+
+.. code-block:: php
+
+    $parameters = [[5, 'foo', 1], [6, 'bar', 2], [7, 'foo', 3], [8, 'bar', 4]];
+    $statement = $connection->prepare(
+        'INSERT INTO test_table (id, name, int_type) VALUES (?, ?, ?)',
+        array("bulkMode" => true));
+    $statement->execute($parameters);
+
+
 Next steps
 ==========