Re: [NOVICE] varchar vs varchar(n)

On Sun, Nov 12, 2017 at 2:34 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

john snow <ofbizfanster@gmail.com> writes:
> do postgresql developers just use varchar instead of specifying a limit n
> when dealing with string types? if so, are there any gotcha's i should be
> aware of?

Generally speaking, I would only use varchar(n) when there is a clear
reason traceable to application requirements why there has to be a
limit, and why the limit should be n and not some other number.
Otherwise you're just creating issues for yourself.  The habit of
inventing arbitrary limits on text column width is just a hangover
from punched-card days.

Actually, Postgres people tend to use "text" rather than unconstrained
"varchar".  In principle those two types behave equivalently; but the
system has to jump through some extra hoops to work with varchar, and
every so often you'll run into a case where "varchar" is not optimized
as well as "text".

                        regards, tom lane