#+TITLE: Sixth - system for data storage, computation, exploration and interaction

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- This is a subproject of [[http://www2.svjatoslav.eu/gitbrowse/sixth/doc/index.html][Sixth]]

- [[http://www2.svjatoslav.eu/gitweb/?p=sixth-data.git;a=snapshot;h=HEAD;sf=tgz][download latest snapshot]]

- This program is free software; you can redistribute it and/or modify
  it under the terms of version 3 of the [[https://www.gnu.org/licenses/lgpl.html][GNU Lesser General Public
  License]] or later as published by the Free Software Foundation.

- Program author:
  - Svjatoslav Agejenko
  - Homepage: http://svjatoslav.eu
  - Email: mailto://svjatoslav@svjatoslav.eu

- [[http://svjatoslav.eu/programs.jsp][other applications hosted at svjatoslav.eu]]


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* Vision / goal
Provide versioned, clustered, flexible, object-relational database
functionality for the [[http://www2.svjatoslav.eu/gitbrowse/sixth/doc/index.html][Sixth computation engine]].

+ I hate object-relational impedance mismatch.

+ I don't like to convert data between persistent database and runtime
  objects for every transaction. How about creating united
  database/computation engine instead to:
  + Eliminate constant moving and converting of data between 2 systems.
  + Abstract away difference between RAM VS persistent storage. Let
    the system decide at runtime which data to keep in what kind of
    memory.

** Inspiration
+ Relational databases:
  + Transactional.
  + Indexable / Quickly searchable.

+ Git (version control system)
  + Versionable
  + Branchable / mergeable.
  + Transparent cansistency, checksumming and deduplication.
  + (Git as a database:
    https://www.kenneth-truyers.net/2016/10/13/git-nosql-database/ )

** Solution (the big idea)
I see 4D data structure.

[[file:data model.png]]

Dimensions:
+ List of all the objecs in the system (rows).
+ List of all declared unique object fields (columns).
+ List of all historical transactions/commits/versions (think of
  sheets of paper).
+ List of all concurrently running branches/threads. Branches can
  appear and merge over time as needed.
+ (Every cell is concrete field value within an object)

Partitioning/clustering:
+ Why not to partition/(load balance) as required across networked
  physical computers along arbitrary dimension(s) declared above ?

Indexing (for fast searching):
+ Why not to index along arbitrary dimensions (as required) ?

Further optimizations:
+ In current early stage, trying to focus on minimum possible set of
  features that would provide maximum possible set of power/benefit :)
+ Once featres are locked. Anything can be optimised. Optimization for
  size (deduplication) can be solved using Git style content
  addressible storage mechanism.
* Current status
- Implemented very simple persistent key-value map.

Long term goal is to implement more advanced features on top of this.

* TODO
** check out Magma
  + http://wiki.squeak.org/squeak/2665