Обсуждение: varchar(n) and text

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varchar(n) and text

От
Yan Cheng Cheok
Дата:
According to http://www.postgresql.org/docs/8.0/interactive/datatype-character.html

I always use TEXT, for column which store text so that I need not to worry on text length.

However, in certain situation, I know that my text length will always < 10 characters

I was wondering, if I using TEXT, will there have any overhead on

(1) storage space?
(2) query performance?
(3) write performance?

Shall I just use varchar(10) ?

Thanks!

Thanks and Regards
Yan Cheng CHEOK

Re: varchar(n) and text

От
Bruce Momjian
Дата:
Yan Cheng Cheok wrote:
> According to http://www.postgresql.org/docs/8.0/interactive/datatype-character.html
>
> I always use TEXT, for column which store text so that I need not to worry on text length.
>
> However, in certain situation, I know that my text length will always < 10 characters
>
> I was wondering, if I using TEXT, will there have any overhead on
>
> (1) storage space?
> (2) query performance?
> (3) write performance?
>
> Shall I just use varchar(10) ?

This is an FAQ, and is mentioned in the manuals.  The short answer is
that there is no different for any of them in any areas, except
documented behavior, e.g. char(10) is always output as 10 characters.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +