Impedance Mismatch?

September 30, 2010


The previous post about Boolean datatype sparkled a lively discussion at comp.databases.theory. Here, I’ll embark upon Tony Andrews comment that SQL DBMS world somehow abhors unary relations. This is very strange from theoretical perspective, as one can expect lower arity relations be prevalent according to Zipf law.

This is one more artifact of infamous impedance mismatch between front-end application and DBMS. The client behavior is imperative: “Tell me if my customer is creditworthy or not, so I can proceed with her application. (I don’t care about the list of all other creditworthy customers!)” . It clearly wants a boolean answer. What database reply might be? “Look, I supplied all the [relevant] information, isn’t decision and taking action your responsibility?”

P.S. We all know that ORM tools (Hibernate, Linq, etc) solved impedance problem already, so the issue is no longer there! Just kidding.

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3 Responses to “Impedance Mismatch?”

  1. Tony Andrews Says:

    Very nice! I remember working with a Principal Oracle Consultant once who refused to accept that it was legal to have a table with just one column. I had to add a redundant “description” column just to get it past him…

  2. Erwin Smout Says:

    By the way.

    I entered something for the algebra puzzles. Like to get some kind of reply, no matter how insulting or depriving.


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