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From:Alec.Cawley Date:March 30 2005 3:48pm
Subject:Re: Index on boolean column
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Du?an Pavlica <pavlica@stripped> 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

Thread
Index on boolean columnDušan Pavlica30 Mar
  • Re: Index on boolean columnAlec.Cawley30 Mar
  • Re: Index on boolean columnMartijn Tonies30 Mar
  • Re: Index on boolean columnbeacker30 Mar
  • Re: Index on boolean columnDušan Pavlica31 Mar
  • Re: Index on boolean columnMartijn Tonies31 Mar
  • Re: Index on boolean columnMartijn Tonies31 Mar
  • Re: Index on boolean columnDušan Pavlica31 Mar
  • Re: Index on boolean columnMartijn Tonies31 Mar
Re: Index on boolean columnMartijn Tonies31 Mar