Sunday, July 30, 2017

Integrity Is Not Only Referential: DBMS vs Application Enforced Constraints

Note: This is 07/30/17 rewrite of a 11/11/12 post to bring it line with McGoveran formal exposition of Codd's real RDM [1] and its interpretation.

 

There is nothing wrong per se with the question in last week's picture, namely:
"Can I ask whether people make use of the functionality provided by the database to ensure adequate data quality. Secondly do people apply this retrospectively as seems quite reasonable to me when a data problem is identified and the source data cleaned up--to do so could prevent future errors. There appears to be a tension between this sort of implementation and at least a perception of flexibility as database changes would be required should additional allowable values be required." --LinkedIn.com
except that it's about time such questions are no longer asked. Unfortunately, they are evidence of the persistent lack of foundation knowledge in the industry for more than five decades. Such knowledge would have obviated such questions.

Sunday, July 23, 2017

This Week

1. Database Truth of the Week

"And [AI] weaknesses there are. Watson requires many months of laborious training, as experts must feed vast quantities of well-organized data into the platform for it to be able to draw any useful conclusions. And then it can only draw conclusions based upon the body of data, or ‘corpus’ (plural: ‘corpora’) that it has been trained on. The ‘well-organized’ requirement is especially challenging for Watson, as unprepared data sets are typically insufficient. As a result, Watson customers must hire teams of expert consultants to prepare the data sets, a time-consuming and extraordinarily expensive process." --Is IBM's Watson a Joke?

Sunday, July 16, 2017

Relations and Relationships Part II

See Relations and the Relational Model

Sunday, July 9, 2017

This Week

1. Database Truth of the Week

"For the operations of a formal system to have inverses within some specific use of that system (like a specific application):
  • The basic elements must be orthogonal (independent), hence the Principle of Orthogonal Design;
  • The combination of basis elements and operations must be expressive enough to represent every aspect of the subject matter, hence the Principle of Expressively Complete Design;
  • And, at the same time, not so expressive that there is more than one way to express each aspect of the subject matter, hence the Principle of Representation Minimality Design.
The basic elements of a relational database is the relation. Adherence to these principles ensure thatthere is a unique relational expression for every aspect of the subject matter--either a base relation or a derived relation--and if there are two ways to derive a derived relation, then those two expressions are provably equivalent (i.e., the differences are merely syntax and never meaningful)." --David McGoveran

Monday, July 3, 2017

New Paper: Logical Symmetric Access, Data Sub-language, Kinds of Relations, Database Redundancy and Consistency

NEW!!! Paper #2 in the Understanding the Real RDM series. NEW!!!   

The data management field cannot and will not progress without educated and informed data professionals and users. UNDERSTANDING THE REAL RDM is a new series of papers that offers informal access to the forthcoming McGoveran interpretation of the formal real RDM envisioned by E. F. Codd (EFC), contrasts it with the current understanding that emerged after EFC's death and demonstrates the practical implications of the differences.

If you are a thinking data professional interested in understanding the scientific foundations of data management, as opposed to the "cookbook" industry practices, these unique papers are a must read. They give you new insights into the RDM--which I call the real data science--and the practical benefits that fail to materialize due to its misuse and abuse promulgated by DBMS vendors, the trade media, "experts" and poor SQL implementations, all of which ignore its formal theoretical grounding from which all the practical benefits derive. You will also learn to minimize the consequences of deficiencies of and optimize the use of SQL.