Martin Mueller <martinmueller@northwestern.edu> writes:
> Are there performance issues with the choice of 'text' vs. varchar and some character limit? For instance, if I have
atable with ten million records and text fields that may range in length from 15 to 150, can I expect a measurable
improvementin response time for using varchar(150) or will text do just or nearly as well.
There is no situation where varchar outperforms text in Postgres.
If you need to apply a length constraint for application semantic
reasons, do so ... otherwise, text is the native type. It's
useful to think of varchar as being a domain over text, though
for various reasons it's not implemented quite that way.
regards, tom lane