On Wed, Sep 12, 2001 at 07:55:05PM +0200, Sander Pilon wrote:
> Dear List,
>
> I need to store a set of flags in SQL, as in 20 true or false
> values. The logical choice seems to be the SET type, but does it
> use an index?
I don't think so... It is implemented as a bitmask behind the scenes.
It *could* use an index (not exactly in the normal way), but my gut
feel is that it doesn't.
> The manual gives an examle where a set is queried with LIKE
> '%flag%'. That scares me a bit, because the table is going to
> contain hundredthousands of rows - and I need to be able to filter
> on these flags effeciently.
>
> I could make 20 separate rows as tinyint, but that seems like a lot
> of overhead.
What sort of overhead? The relational model suggests that you might
want to use multiple rows in a separate table that you can join with
the main table.
MySQL is rather fast, even with a lot of data thrown at it. Might be
worth a try.
Jeremy
--
Jeremy D. Zawodny, <jzawodn@stripped>
Technical Yahoo - Yahoo Finance
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