Re: Generic design: char vs varchar primary keys

On Thursday 04 Aug 2011, Josh Kupershmidt wrote:
> 2011/8/3 Raj Mathur (राज माथुर) <raju(at)linux-delhi(dot)org>:
> > Can you point me to any pages that explain the difference between
> > using, say CHAR(8) vs VARCHAR(8) as the primary key for a table?
> > Is there any impact on the database in terms of:
> >
> > - Speed of indexed retrieval
> > - Speed of join from a referencing table
> > - Storage (I presume VARHAR(8) would have a slight edge, in
> > general) - Any other issue
> I suspect the tiny size differences between char(8) and varchar(8)
> are going to be negligible. In fact, this post talks precisely about
> this concern, and more:
>
> http://www.depesz.com/index.php/2010/03/02/charx-vs-varcharx-vs-varc
> har-vs-text/
>
> Personally I'd be most worried about the different semantics of the
> types (i.e. treatment of trailing spaces), and perhaps the ease of
> expanding the length constraint in the future.

Thanks, that's useful for benchmarking the various textual data types.
Anything specific about using CHAR vs VARCHAR for primary keys that are
going to be referenced from multiple tables that comes to mind?

Regards,

-- Raj
--
Raj Mathur raju(at)kandalaya(dot)org http://kandalaya.org/
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