Re: fixed-length row

Richard Huxton wrote:
> On Thursday 15 January 2004 14:17, David Garamond wrote:
> > The MySQL manual recommends that we create a "fixed-length row" if
> > possible, for speed (especially scanning speed). A fixed-length row is a
> > row which is comprised of only fixed-length fields. A fixed-length field
> > takes a fixed amount of bytes for storage (e.g. INT = 4 bytes, CHAR(M) =
> > M bytes, etc).
> >
> > Is there a similar recommendation in PostgreSQL? I notice that most data
> > types are stored in variable-length mode anyway (is cidr and inet data
> > types fixed-length?)
>
> Not really - there have been various discussions about timing differences
> between char() and varchar() and I don't recall one being noticably faster
> than the others.
>
> > Is there a command/query in psql which can show storage requirement for
> > each field? For example:
>
> No, but there's stuff in the archives, and I think something on techdocs too.

FAQ item 4.14 covers this, and reports CHAR() and VARCHAR() have the
same performance characteristics.

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