> I guess it depends on what you're using it for -- disk space
> is cheap and
> abundant anymore, I can see some advantages of having it
> computed only once
> rather than X times, where X is the number of SELECTs as that
> could get
> costly on really high traffic servers.. Costly not so much for simple
> computations like that but more complex ones.
Once and for all forget the argument in database technology, that disk space
is cheap in regard to $/Mb. That is not the question. The issue is:1. amout of rows you can cache2. number of rows you
canread from disk per second (note that it is not pages/sec)3. how many rows you can sort in memory
In the above sence disk space is one of the most expensive things in a
database system. Saving disk space where possible will gain you drastic
performance advantages.
Andreas