Message-ID: <54354A73.6030607@dunslane.net>
Date: Wed, 08 Oct 2014 10:30:11 -0400
From: Andrew Dunstan <andrew@dunslane.net>
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To: emilu@encs.concordia.ca
CC: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: char(N), varchar(N), varchar, text
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On 10/08/2014 10:22 AM, Emi Lu wrote:
> Good morning,
>
> For performance point of view, are there big differences between:=20
> char(N), varchar(N), varchar, text?
>
> Some comments from google shows:
> No difference, under the hood it's all varlena. Check this article=20
> from Depesz:=20
> http://www.depesz.com/index.php/2010/03/02/charx-vs-varcharx-vs-varchar-v=
s-text/
> A couple of highlights:
>
>     To sum it all up:
>
>       * char(n) =96 takes too much space when dealing with values
>         shorter than n, and can lead to subtle errors because of
>         adding trailing spaces, plus it is problematic to change the limit
>       * varchar(n) =96 it's problematic to change the limit in live
>         environment
>       * varchar =96 just like text
>       * text =96 for me a winner =96 over (n) data types because it lacks
>         their problems, and over varchar =96 because it has distinct name
>
>     So, can I assume no big performance differences?
>     Thanks alot!
>     Emi
>


Why do you need to ask if you already have the answer? Depesz is right.

cheers

andrew


--=20
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