The problem is that he has it as a primary key, so he wants it to be unique as well as
indexed. The best solution (and MUCH MUCH MUCH more efficient) would be to hash each of
the four columns, and create a primary key on that. Integer keys are much faster and
memory-efficient than string keys.
Steve Meyers
> -----Original Message-----
> From: Chris Bolt [mailto:chris.lists@stripped]
> Sent: Saturday, October 20, 2001 8:31 PM
> To: mysql@stripped
> Subject: RE: Length limit of 500 on primary keys?
>
>
> > Is there a way to raise this limit? We have some tables with
> columns that
> > are VARCHAR(200), and need to make a primary key based on
> combinations of
> > these columns (in some cases, upto 4 columns), and MySQL
> complains for all
> > of these table definitions that "Specified key was too long. Max key
> > length is 500".
>
> Why do you need to index the entire column? You can just index a prefix of
> the column, like the first 125 bytes of each column.
>
>
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