Philosophy

If you see a comment like “X is a bad idea” this does not mean “some mechanism that is vaguely ‘not X’ is a good idea”.

If, for example, I say:

“Histograms will not work well on character strings that are more than 32 bytes long and generally similar in the first 32 bytes”

that is absolutely not the same as saying

“It’s a good idea to create histograms on character strings that are less than 32 bytes long.”

If this were a purely mathematical world we could invoke symbolic logic and point out:

(A => B) <=> (¬B => ¬A)

which means my statement is equivalent to:

if you have a histogram that is working well then the data is not character strings of more than 32 bytes with generally similar values in the first 32 bytes”

Of course, being Oracle, you may find that someone, somewhere, has exactly such a histogram that appears to work brilliantly for them – but that will be because the optimizer has messed up the arithmetic so much that they are getting a great execution plan for completely the wrong reason … so they need to watch out for the next upgrade or patch release in case the optimizer gets enhanced.

[The Philsophy Series]

Here’s a useful description I heard recently from philosopher Daniel Dennett:

The canons of good spin:

1. It is not a bare-faced lie
2. You have to be able to say it with a straight face
3. It has to relieve skepticism without arousing curiosity
4. It should seem profound

It seems to describe a lot of the stuff that our industry publishes on the internet.

[Back to Philosophy  - 11]

The English language is full of irregular verbs, for example: I am hypothesising about possible explanations You are guessing He’s talking rubbish [Back to Philosophy 10] Filed under: humour, Philosophy

The most significant question to ask when thinking about adding a new index: “Will the index eliminate significantly more work than it introduces (at the moments when it really matters) ?” A few examples of “moments that matter”: Bulk housekeeping Highly concurrent OLTP activity Frequent high-precision reporting Acceptance testing for side effects [Back to Philosophy [...]