Big Data is not Data Warehousing, it is not the evolution of Data Warehousing and it is not a sensible and coherent alternative to Data Warehousing. No matter what certain vendors will put in their marketing brochures or stick up their noses.
In spite of all of the high-visibility screw-ups that have carried the name of Data Warehousing, even when they were not Data Warehouse projects at all, the definition, strategy, benefits and success stories of data warehousing are known, they are in the public domain and they are tangible.
Data Warehousing is a practical, rational and coherent way of providing information needed for strategic and tactical option-formulation and decision-making.
Data Warehousing is a strategy driven, business oriented and technology based business process.
We stock Data Warehouses with data that, in one way or another, comes from internal and optional external sources, and from structured and optional unstructured data. The process of getting data from a data source to the target Data Warehouse, involves extraction, scrubbing, transformation and loading, ETL for short.
Data Warehousing’s defining characteristics are:
Subject Oriented: Operational databases, such as order processing and payroll databases and ERP databases, are organized around business processes or functional areas. These databases grew out of the applications they served. Thus, the data was relative to the order processing application or the payroll application. Data on a particular subject, such as products or employees, was maintained separately (and usually inconsistently) in a number of different databases. In contrast, a data warehouse is organized around subjects. This subject orientation presents the data in a much easier-to-understand format for end users and non-IT business analysts.
Integrated: Integration of data within a warehouse is accomplished by making the data consistent in format, naming and other aspects. Operational databases, for historic reasons, often have major inconsistencies in data representation. For example, a set of operational databases may represent “male” and “female” by using codes such as “m” and “f”, by “1” and “2”, or by “b” and “g”. Often, the inconsistencies are more complex and subtle. In a Data Warehouse, on the other hand, data is always maintained in a consistent fashion.
Time Variant: Data warehouses are time variant in the sense that they maintain both historical and (nearly) current data. Operational databases, in contrast, contain only the most current, up-to-date data values. Furthermore, they generally maintain this information for no more than a year (and often much less). In contrast, data warehouses contain data that is generally loaded from the operational databases daily, weekly, or monthly, which is then typically maintained for a period of 3 to 10 years. This is a major difference between the two types of environments.
Historical information is of high importance to decision makers, who often want to understand trends and relationships between data. For example, the product manager for a Liquefied Natural Gas soda drink may want to see the relationship between coupon promotions and sales. This is information that is almost impossible – and certainly in most cases not cost effective – to determine with an operational database.
Non-Volatile: Non-volatility means that after the data warehouse is loaded there are no changes, inserts, or deletes performed against the informational database. The Data Warehouse is, of course, first loaded with cleaned, integrated and transformed data that originated in the operational databases.
We build Data Warehouses iteratively, a piece or two at a time, and each iteration is primarily a result of business requirements, and not technological considerations.
Each iteration of a Data Warehouse is well bound and understood – small enough to be deliverable in a short iteration, and large enough to be significant.
Conversely, Big Data is characterised as being about:
Massive volumes: so great are they that mainstream relational products and technologies such as Oracle, DB2 and Teradata just can’t hack it, and
High variety: not only structured data, but also the whole range of digital data, and
High velocity: the speed at which data is generated, transmitted and received.
These are known as the three Vs of Big Data, and they are subject to significant and debilitating contradictions, even amongst the gurus of Big Data (as I have commented elsewhere: Contradictions of Big Data).
From time to time, Big Data pundits slam Data Warehousing for not being able to cope with the Big Data type hacking that they are apparently used to carrying out, but this is a mistake of those who fail to recognise a false Data Warehouse when they see one.
So let’s call these false flag Data Warehouse projects something else, such as Data Doghouses.
“Data Doghouse, meet Pig Data.”
Failed or failing Data Doghouses fail for the same reasons that Big Data projects will frequently fail. Both will almost invariably fail to deliver artefacts on time and to expectations; there will be failures to deliver value or even simply to return a break even in costs versus benefits; and of course, there will be failures to deliver any recognisable insight.
Failure happens in Data Doghousing (and quite possibly in Big Data as well) because there is a lack of coherent and cohesive arguments for embarking on such endeavours in the first place; a lack of real business drivers; and, a lack of sense and sensibility.
There is also a willing tendency to ignore the advice of people who warn against joining in the Big Data hubris. Why do some many ignore the ulterior motives of interested parties who are solely engaged in riding on the faddish Big Data bandwagon to maximise the revenue they can milk off punters? Why do we entertain pundits and charlatans who ‘big up’ Big Data whilst simultaneously cultivating an ignorance of data architecture, data management and business realities?
Some people say that the main difference between Big Data and Data Warehousing is that Big Data is technology, and Data Warehousing is architecture.
Now, whilst I totally respect the views of the father of Data Warehousing himself, I also think that he was being far too kind to the Big Data technology camp. However, of course, that is Bill’s choice.
Let me put it this way, if Oracle gave me the code for Oracle 3, I could add 256 bit support, parallel processing and give it an interface makeover, and it would be 1000 times better than any Big Data technology currently in the market (and that version of Oracle is from about 1983).
Therefore, Data Warehousing has no serious competing paragon. Data Warehousing is a real architecture, it has real process methodologies, it is tried and proven, it has success stories that are no secrets, and these stories include details of data, applications and the names of the companies and people involved, and we can point at tangible benefits realised. It’s clear, it’s simple and it’s transparent.
