Confessions of an IT Manager_Phil Factor

When the Fever is Over, and one's
Work is done
First published 29 May 2008
Like the mumps, 'EAV' disease strikes the afflicted
only once, but the memories of suffering and delirium
last forever.
There comes a time in the life of anyone working with databases when they
are struck with a peculiar mental aberration. For want of a better term, it is
usually called 'One True Lookup Syndrome' or OTLS. It is in the same league
as the rather more severe affliction 'EAV disease' (Entity Attribute Value). It is
like measles or mumps in that it afflicts the sufferer just once and he, or she, is
thereafter immune. The memory of the suffering and delirium is retained,
however, and the feelings of embarrassment.
The sufferer is easy to recognise. He shakes his head in wonder,
saying "This is like, such a cool idea, how come nobody has thought of
it before? It is like wow! I mean it is so neat." A classic symptom of the
disease is that they will sidle up to you and ask how to patent software
ideas. We grey-muzzles will shake our heads sadly, with a pitying
smile, and just mutter solemnly 'One true lookup table'.
Usually, OTLS comes about when one is forced to create a number of
simple lookup tables which contain a code and a name. One gets the sudden
flash of inspiration that one could roll them all into one lookup table, with a
unique identifier for each row, and a type field, thereby saving the chore of
creating and maintaining a number of tables. EAV disease, like OTLS, both
tend to be the result of pressure from programmers to push their OO designs
back into the relational database. There is loose talk of 'persisting object data in
a data store', as though one was storing apples in a shed. It also comes about
when a development team attempts an 'Agile' development before they've fully
understood the data model.
I'm a recovering EAV sufferer and I remember the first symptoms well. I
was under stress, working with a systems analyst whose analysis skills were at
about the same level as a dead sheep's. The database was for an internet system
for car dealerships, selling second-hand cars. It was supposed to value your
stock, and to enable groups of dealers to supply a punter with the exact car he