At a talk at the recent TDWI show, consultant Joshua Greenbaum, an analyst with Enterprise Applications Consulting (who?) managed to bemoan the cost of data warehouses, but then demonstrates a seeming lack of knowing exactly what one is by claiming that the alternative is to do “simple analyses of transactional data”. Well Joshua, that is called an operational data store, and indeed it has a perfectly respectable role if all you want to do is to look at a single operational system for operational purposes. However a data warehouse fulfils quite a different role: it takes data from many different sources, allows analysis across these inconsistent sources and also should provide historical context e.g. allowing comparisons of trends over time. You can’t do these things with an operational data store.
Hence it is not a case of “ODS good, data warehouse bad” – instead both structures have their uses. Of course Joshua is right in saying that data warehouse success rate is not great, but as I have written elsewhere, it is not clear whether data warehouse projects are really any worse than IT projects in general (admittedly, that is not setting the bar real high). Perhaps Joshua was misquoted, but I would have expected something more thoughtful from someone who was an analyst at Hurwitz. Admittedly he was an ERP (specifically SAP) analyst, so perhaps has a tendency to think of operational things rather than things wider than ERP. Perhaps he is suffering from the same disease that seems to affect people who spend too much time on SAP.