Transactions
============

ArcaneDB supports both implicit and explicit transaction management.

Implicit Transactions
---------------------

Every data-modifying statement automatically participates in an implicit transaction. Calling ``commit!`` outside of an explicit ``begin!`` block finalises the implicit transaction, persisting all changes made since the last commit.

.. code-block:: aql

   insert into Names (first_name: "Charlie", last_name: "Parker");
   insert into Names (first_name: "Charlie", last_name: "Brown");
   commit!;

Explicit Transaction Blocks
---------------------------

For operations that must succeed or fail atomically, an explicit transaction block can be declared using ``begin!`` and closed with either ``commit!`` or ``rollback!``.

**Syntax:**

.. code-block:: none

   begin!;
       <statements>;
   commit!;

   begin!;
       <statements>;
   rollback!;

**Commit example:**

.. code-block:: aql

   begin!;
       insert into Puddles (
           [x: 15.4, y: 45.8],
           [x: 21.2, y:  3.2],
           [x:  4.5, y:  2.4]
       );
   commit!;

**Rollback example:**

.. code-block:: aql

   begin!;
       insert into Puddles (x: 12.2, y: 4.5);
       insert into Puddles (
           [x: 14.4, y: 42.5],
           [x: 20.2, y:  3.1],
           [x:  4.0, y:  2.3]
       );
   rollback!;

When a ``rollback!`` is issued, all changes made within the enclosing ``begin!`` block are discarded and the database is returned to its state at the time of the ``begin!``.