Thread

Re: [HACKERS] varchar/char size

Bruce Momjian <maillist@candle.pha.pa.us> — 1998-01-08T03:17:50Z

> 
> > Does someone want to remind me why we allocate the full size for char()
> > and varchar(), when we really can just allocate the size of the given
> > string?
> > I relize char() has to be padded, but why varchar()?
> 
> > In my experience, char() is full size as defined by create, and
> > varchar() is the the size of the actual data in the field, like text,
> > but with a pre-defined limit.
> 
> Well, in many relational databases access can be optimized by having
> fixed-length tuple storage structures. Also, it allows re-use of deleted
> space in storage pages. It may be that neither of these points have any
> bearing on Postgres, and never will, but unless that clearly the case then
> I would be inclined to keep the storage scheme as it is currently.

With Ingres and Informix char() is fixed size, while varchar() is
VARiable size.

-- 
Bruce Momjian
maillist@candle.pha.pa.us