Databasen - Revisited
wiggly at wiggly.org
Thu Oct 19 10:20:39 BST 2006
Matt Sergeant wrote:
> Q: What is wrong with the following setup:
> CREATE TABLE Month (
> id INTEGER PRIMARY KEY,
> name VARCHAR(16),
> shortname VARCHAR(3)
> INSERT INTO Month VALUES (1, "January", "Jan");
> There are lots of fairly obvious right answers (localisation would be
> one obvious one), but most people won't get the fact that the primary
> key index is a bad thing, because the entire table fits into a single
> page of pretty much every DB I know, so index access is actually slower
> than a full table scan.
> If they answer with that, it's an instant hire (though I've never given
> this question to anyone. 9 out of 10 DBAs wouldn't even get it, sadly).
Any decent database's query planner won't use the index in that case
though, so I don't think it's an 'instant hire' answer.
I take your point about internationalisation but then, I wouldn't hold
those textual names in the database anyway, my application code is where
the i8ln should be occuring.
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