Re: Varchar vs text

Thanks for elaborating on that Tom. I understand what it means by extension
now.

The reason I looked into it in the first place was because someone at work
said that varchar was an alias for text, which didn't quite sound right.
And I had automatically used the data-type "text" for any varying text
fields since there is no performance/storage hit in PostgreSQL for such
data, unlike some other RBDMSs. It's interesting to know of the
non-nativity of varchar, even if the practical differences are negligable.
:)

Thanks again

Thom

2009/1/27 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>

> Thom Brown <thombrown(at)gmail(dot)com> writes:
> > The reason I ask is because the documentation says "If character varying
> is
> > used without length specifier, the type accepts strings of any size. The
> > latter is a PostgreSQL extension." I wasn't sure if such an extension
> meant
> > there was a level of over-head involved, or reduced its indexability.
>
> "Extension" means "it's not in the SQL standard". It's not meant to imply
> anything about performance.
>
> There is some potential overhead from using varchar instead of text
> because of the extra dummy cast nodes that are likely to be present in
> your query expressions (since all the native functions are declared to
> take/return text, not varchar). In most cases I'd think you'd be
> hard-put to measure any difference though.
>
> regards, tom lane
>