PhD ThesisWhen information is stored in a computer it can usually be
organised in many different ways. If the information is
used for a number of different purposes the ideal
organisation is not always obvious. It will depend on how
often various parts of the data are used, how often they are
changed, and the amount of data taking part in each
transaction. It may be difficult to predict these
parameters in advance, especially in data-base applications
where the pattern of use may change as time goes by.
Ultimately, one can visualise systems which can
automatically choose the optimum
can substantially assist in the
representation, or
choice. A step in
which
this
direction, which could itself find immediate application, is
to find a practical way to tailor programs to a particular
data organisation. The thesis describes an experimental
system which does this for a limited range of programs, and
the work which lead up to it. Both data retrieval and
simple updates are considered.
One prerequisite is a method of writing the program so that
it does not depend on the way that the data is stored. A
number of data-base systems achieve this independence by
describing the data as a collection of relations. These
systems and the background to them are reviewed. The
experimental system is loosely based on the use of
relations, but some modifications have been made to make the
processing simpler and so that the characteristics of the
data organisation can be described. The system incorporates
the representation into the program and produces a tailored
version which is expressed in abstract, Algol-like code.
The result is intended to be similar to code which a human
programmer might write in similar circumstances, but as far
as possible ignoring the details of any particular
implementation.IBM, Advanced Education Scheme
