On Tue, 2004-04-27 at 23:47, Jonathan Gardner wrote:
I've just discovered OLAP and it looks like a competing technology with
materialized views.
Yes. Read up some more, but don't get sucked in by the marketing.
In a nutshell, OLAP seems to be "pre-storing" the results of potential
queries. When queries are made with those conditions, then the pre-stored
results are used. It seems most common for join conditions or aggregates
with conditions. (Corrections welcome...)

This seems like a generally useful tool. I expect PostgreSQL should one day
have a feature like this.

OLAP usage would basically be describing how the data fits together and
predicting what kinds of queries will be made. Then, internally the
implementation would decide what data should be cached. Perhaps it can do
some analysis of the data and the queries being run to come up with a fair
compromise.

Materialized Views are a simpler concept, but of limited usefulness. Having
a bunch of materialized views that are very similar would be less efficient
overall than having OLAP configured properly.

Questions:
(1) Has anyone been doing any work or serious thought on anything like this?
Yes. There is Relational OLAP (ROLAP) and Multidimensional OLAP (MOLAP).
PostgreSQL can be used as a ROLAP server.
(2) Should I be focusing on OLAP rather than materialized views? With
materialized views, a few specific queries work really well, but related
queries get no benefit. Apparently, with OLAP, a whole class of queries
will get a huge boost. I'm not certain that OLAP and materialized views are
entirely different.
No, your work is well received.
(3) I can't seem to find the paper on the twelve laws of OLAP, but it gets a
lot of mentioning. Does anyone know where I can obtain it?
Written by Ted Codd, but not nearly as interesting as his earlier work.
Future Thoughts:
OLAP relies on knowing how the data fits together and what kinds of queries
are being done. It could be possible, just by analyzing the queries being
run, to have OLAP automatically kick in without user intervention.

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