Du?an Pavlica <[EMAIL PROTECTED]> wrote on 30/03/2005 16:35:40:
> Hello,
>
> maybe this is a silly question but how useful it is to create
> indexes on columns containing only values 0 and 1 (true and false)?
Since I believe that MySQL ignores indexes if it expects to get more than
30% hits, it will probably be ignored unless the distribution of 0s and 1s
is very skewed. If you only have a tiny fraction of (say) 1s, it might be
useful to extract that tiny fraction - but useless for the opposite.
Alec
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