Re: [NOVICE] varchar vs varchar(n) - Mailing list pgsql-novice

From Tom Lane
Subject Re: [NOVICE] varchar vs varchar(n)
Date
Msg-id 21800.1510515292@sss.pgh.pa.us
Whole thread Raw
In response to [NOVICE] varchar vs varchar(n)  (john snow <ofbizfanster@gmail.com>)
Responses Re: [NOVICE] varchar vs varchar(n)  (john snow <ofbizfanster@gmail.com>)
List pgsql-novice
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


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