Friday, April 11, 2014

Weekly Update

1. Quote of the Week
Now that we have seen a lot of information about NoSQL databases, it is interesting to drop back and look around at how much NoSQL stuff we already have in our organizations. I had never thought of a file system as a database, but it is. The comparison is fascinating. File systems don’t impose any structure on the data that is stored in any given file. There is a key value relationship to each file. There is little control over concurrency beyond file locking. This is very similar to NoSQL, with locking only at the aggregate level. File systems are cheap; everyone has one and they hold huge amounts of data on multiple nodes. --Book review, NoCOUG Journal

2. To Laugh or Cry?
Find GUID in Database

3. Online exchanges

4. Interesting elsewhere (corrected first link and added a second):

5. And now for something completely different
Joe Biden wants to nominate Obama for sainthood
The VP of the world's "superpower".
Stanford opening new lab to study bad science
And tomorrow we'll need a lab to study bad science in the study of bad science.

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  1. The "find GUID in database" was a real jawdropper wasn't it ?

    The poster originally even managed to have his full work email address exposed. So I asked him whether this email address was indicative of the company where this disaster had happened. The next day, the full email address _AND_ my entire reply had been removed. It was one of the major players in the business of certificates and authenticity.

    1. It would have been much better had it surprised me. But the fact that it does not is not.

  2. Isn't that 5th NF link supposed to be under "laugh or cry"?

    1. Probably, but it's usually tough to decide between Quotes, Laugh/Cry, Online or "to debunk".

  3. Re Big data 5nf-fifth normal form:
    The blogger addresses a mistake, but other than that their analysis is wrong.
    The mistake is what Codd in 1970 called "the connection trap": 'This trap may be described in terms of the following example. Suppose each supplier description is linked by pointers to the descriptions of each part supplied by that supplier, and each part description is similarly linked to the descriptions of each project which uses that part. A conclusion is now drawn which is, in general, erroneous: namely that, if all possible paths are followed from a given supplier via the parts he supplies to the projects using those parts, one will obtain a valid set of all projects supplied by that supplier'.
    The way in which this can be related to 5nf is that if we knew that the example's original table was _not_ in 5nf and _specifically_ so because its associated meaning could be expressed as the AND of its binary projections' meanings then the JOIN of those projections _would_ have the original's meaning. Or per Codd's next sentence: 'Such a conclusion is correct only in the very special case that the target relation between projects and suppliers is, in fact, the natural composition of the other two relations'.
    So the mistake is not "violation of 5nf". It is just not knowing what one's tables mean. (In fact the unjustified assumption is that a certain something _isn't_ in 5nf in a certain way when it actually _is_ in 5nf.)

    1. This comment has been removed by the author.

    2. Glad someone could explain it. I was lost as soon as the first table was split into those three, when the first table appeared to be stating a single fact per row.

    3. Stay tuned -- a more detailed debunk is forthcoming.