Simplicity

1
Simplicity
in Relational Database Systems
David Livingstone
UK Systems Society11th International
ConferenceSeptember 2007, Oxford
2
Background

• DB research project achieving simplicity is
  inherent.
• A PhD built on this find simple solution to a
  problem.
• Draft PhD chapters assumed simplicity.
• Not acceptable !

What is this simplicity ? Why is it important
?What is the basis ? What is the aim
? Underlying suspicion - simplicity is not
realistic. Simplicity easy research to do -
copout ! results in not-very-useful
product - trivial ! academics dont do
easy things !
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Themes of Presentation
Part of a larger research project.

• 1. PhD a (database) problem its
  solution.
• 2. Simplicity what is it,
  how do we get it ?
• 3. System what are the elements, and how
  should they be joined up ?

System Relational Model Elements Data
Structures Operators Joining Up Assignments
of Algebraic Expressions
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Simplicity is a Virtue

• If projects or programmes are overly complex,
  there is a good chance they are simply wrong.
  (Brian Jones, IBM).
• Complexity leads to design problems greater
  risk of error. (Martyn Thomas, Praxis MD).
• There are no complex systems that are secure.
  Complexity .. almost always comes in the form of
  features or options. (Ferguson
  Schneier).

.. that a product with fewer features might be
more usable, more functional, superior .. is
considered blasphemous. (Donald Norman).
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Background Third Manifesto

• Specification of a replacement for
  Object-Relational SQL.
• Motivation ? conceptually simpler, more
  functional. Adhere to relational principles.
• Purely logical model implementation not
  considered. Containers orthogonal
  to scalar values.

Any kind of data can be a scalar e.g. pictures,
piece of music, video.
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Third Manifesto Principles

• 1. Fred Brooks (from The Mythical Man-Month)
  
• Because ease of use is the purpose, the ratio of
  function to conceptual complexity is the ultimate
  test.
• Simplicity and straightforwardness proceed from
  conceptual integrity. It is better to reflect one
  set of design ideas than to have many good but
  uncoordinated ideas.

• 2. Wittgenstein
• All logical differences are big differences. In
  logic, we are not making subtle distinctions.
• Note program bugs are usually small
  differences.

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What is the PhD Problem ?

• Want to be able to nest all possible kinds of
  container.

11 different kinds of container. How to add them
while providing simplicity and retaining
functionality ?
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What is it that should be Simple ?

• Mental Model Principle - People understand
  interact with systems environments based on
  mental representations developed from
  experience. (Universal Principles of
  Design).
• A good conceptual model is .. fundamental to
  good design. Good designers
  present explicit conceptual models for users.
• (D. Norman - Design of Everyday Things).

Answer Users Conceptual Model of Software
System. Not the software design or
code.Not necessarily lean software.
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Criteria of Simplification

• Parsimony of concepts.
• Straightforwardness of concepts. Simplicity.
  Terseness. Elegance.
• Generality of concepts. No limitations or
  exceptions.
• Orthogonality. Each concept is independent of
  every other concept, so that they can be combined
  in any arbitrary way.
• Uniformity. Consistency regularity in
  expressing concepts.

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What Simplicity is NOT

• NOT Minimalism, which provides simplicity by
  limiting explicit functionality (c.f.
  Essentiality).
• NOT (necessarily) intuitive. Intuition
  is simply a state of subconscious knowledge
  that comes about after extended practice.
  (Donald Norman).
• WRONG experience may require un-learning.E.g.
  Proponents of OO Programming insist on need to
  think in OO terms to be able to program
  effectively.
• IRREDUCIBLE MINIMUM of Simplicity. Everything
  should be made as simple as possible, but not
  simpler. (Albert Einstein).

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Achieving Simplicity in Physics

• Raise level of abstraction.
• Raise level of generality.
• Example electricity magnetism are special
  cases of electromagnetism.
• Example unify the 4 forces of nature into
  one. (Needs 10 or 26 dimensions !)

Beauty simplicity, elegance, symmetry. (Hype
rspace by Michio Kaku). Einstein developed
relativity because symmetry was more fundamental
than Newtonian space-time. ? reform space-time
to fit symmetry.
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Achieving Simplicity in a Software System

• Separate the users conceptual model from its
  implementation.
• Raise the level of abstraction and
  generalityapply essentiality beautyderive
  simple conceptual taxonomy for the user model.
• Check the users conceptual model against -
  conceptual integrity, - simplification
  criteria.
• Implement the model with as much automation as is
  feasible. Defaults can be useful. May need
  complex software to get a simple conceptual
  model. Analogy of car.

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Complexity versus Simplicity
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Simpler Database System
PhD 11 ? 3Sequences, bags sets of data.
Joining Up of Elements Assignment
statements only.
Variable ? algebra expression
- generalised assignments, - nested assignments.