Historical notes
================

Persistence 1.
--------------

* Used by CMB.

Persistence 2. CmbPrst.
--------------

* Internal storage of CMB.

Persistence 3. ptvp3.
---------------------

* Cluster of backed-up-on-disk dictionaries.
* Used by CBMB.

Persistence 4. ptvp3.4. ShelveSQLite.
-------------------------------------

* SQLite-based analogue of :code:`shelve` module.
* Used by v6x12 implementation of CBMB.

Persistence 5. ptvp3.5.
-----------------------

* First :code:`async` database in the line.
* File stream storage.

Persistence 5 early release candidates.
--------------------------------------

* Prevents database corruption.

Persistence 5 1.0 (5.1.0).
-------------------------

* ACID compliant.
* Reduced or none blocking code.

Persistence 5 1.1 (5.1.1).
-------------------------

* Non-nightly support for transactions.
* Instrumentation support.

Proposed future versions
========================

Persistence 5 1.2.
------------------
* More abstract concepts (expansion of :code:`VirtualConnection` and :code:`LineRequest`).

Persistence 5 2.0.
------------------
* Any future breaking changes are going to be listed here.