1. Database Truth of the Week

“... [one] limitation imposed by set semantics is the inability to express the concept of a computer variable to which values can be destructively assigned (or "updated") ... variables can be expressed in logic, but they cannot be expressed in elementary set theory, or first order predicate logic (FOPL) -- the foundations of the RDM. Other, more expressively powerful systems are required. Unfortunately, such powerful formal systems do violence to the RDM and its intent.” --David McGoveran

2. What's Wrong With This Database Picture?

"In my experience, using an object model in both the application layer and in the database layer results in an inefficient system. This are my personal design goals:
- Use a relational data model for storage.
- Design the database tables using relational rules including 3rd normal form
- Tables should mirror logical objects but any object may encompass multiple tables- Application objects, whether you are using an OO language or a traditionallanguage using structured programming techniques should parallel application needs which most closely correspond to individual SQL statements than to tables or "objects". --LinkedIn.com

"In a book I am reading (QUERYING SQL SERVER 2012) the author talks about theory of how databases work. He mentions relations, attributes and tuples etc. He frequently stresses the fact that some aspect of T-SQL is not relational. Like in the following excerpt:

"T-SQL also supports an object called a cursor that is defined based on a result of a query, and that allows fetching rows one at a time in a specified order. You might care about returning the result of a query in a specific order for presentation purposes or if the caller needs to consume the result in that manner through some cursor mechanism that fetches the rows one at a time. But remember that such processing isn’t relational. If you need to process the query result in a relational manner--for example, define a table expression like a view based on the query--the result will need to be relational. Also, sorting data can add cost to the query processing. If you don’t care about the order in which the result rows are returned, you can avoid this unnecessary cost by not adding an ORDER BY clause."

I would like to know, since every implementation of SQL pretty much has an ORDER BY clause which makes it non-relational, why does it even matter that (the set after ORDER BY is used) its not relational anymore since its like that everywhere? I can understand if he said it was non-standard, for example using != instead of <> for inequality because that affects portability etc., but I do not understand why something is better being relational. Please enlighten." --stackoverflow.com

1. Database Truth of the Week

"Semantic correctness: every interpretation of the symbols (meaning assignment and truth value assignment) that makes the axioms true, makes the theorems true. When we extend a logical data model with semantics (specific to the subject matter and its "business" rules) via constraints, those constraints become axioms that must be true." --David McGoveran

"Hadoop seems to take over relational database, as Hbase can store even unstructured data whereas relational data warehouse limits to structured data ... handles traditional structured data just fine, albeit in a different way than a RDBMS ... EDW vendors [will] incorporate Hadoop framework into their core architectures to enable advanced and high performance analytics."

"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

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?