Thursday, December 22, 2005

A Christmas Message

I must have nodded off in the armchair after a glass or two of seasonal cheer when I was confronted by an apparition - a ghost of data warehouses past. He was not a pretty sight - dating back to the mid 1990s and with a grumpy attitude. In those days all you had was a database and a compiler, and a customer who wanted to somehow bring together data from multiple, incompatible systems. There were no ETL tools, no data warehouse design books and little in the way of viewing the data once you had managed to wrestle it into the new data warehouse, just reporting tools that just about saved you coding SQL but confronted users with the names of the tables and columns, usually restricted to eight characters. Those were the days, a salutary reminder of how primitive things were.

Following this was a ghost of data warehouses present. This was a much chirpier looking fellow, who could gain access to data from even devious and recalcitrant source systems via ETL tools like Ascential, and had at least some idea how to design the warehouse. These designs had suitably festive names: "snowflake schema", "star schema". If we had a reindeer schema then it would have completed the festive scene. This wraith had a sackful of reporting tools to access the data, count it, mine it and graph it. Yet not all was well - the pale figure seemed troubled. Every time the source systems changed, the warehouse design was impacted, and teams of DBA elves had to scurry around building tables, sometimes even dropping them. Moreover the pretty reporting tools were completely unable to deal with history: when reports were needed from past seasons there was no recollection of the master data at the time, and it did not reflect the current structures. The only ones really happy here were the DBA elves, who busied themselves constructing ever more tables and indices - they love activity, and they were content.

Last came a ghost of data warehouse future. In this idyllic world, changes in the source systems have no effect on the warehouse schema at all. The warehouse just absorbs the change like a sponge, and can produce reports to reflect any view of structure, present, past or even future. There are less DBA elves around, but they have discovered new things to do with their free time - with SAP up to 32,000 tables these days, there is no unemployment in DBA elf land. Best of all the customers are happy, as they can finally make sense of the data as quickly as their business changes. New master data can be propagated throughout their enterprise like so much fairy dust. I have seen the future of data warehousing, and it is adaptive.

Well, enough of that. Time to talk turkey, or at least eat it. While doing so, it may be relaxing to look back at some of the turkeys that our industry has managed to produce over the years. Human nature being what it is, there is more than one web site devoted to the follies of the technology industry, and even to the worst software bugs. Have fun reading these. I recall being told by a venture capitalist that the dot-com boom of the late 1990s proved that "in a strong enough wind, even turkeys can fly". These are some that did not.

I would like to wish readers of this blog and very happy Christmas.


Anonymous Anonymous said...

After 10 years of designing and building successful data warehouses it frustrates me that many still base their designs on business processes (constantly changing) rather than business objects (relatively stable). C'mon its not rocket science. Design to meet the need. Operational systems support business processes, Data Warehouses support decision process which are based on business object information. And design for the end users, not for the IT gyuys. ETL should be complex so that reporting is easy and consistant.

7:25 PM  

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