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 <t...@sss.pgh.pa.us> > Thom Brown <thombr...@gmail.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 >
