Re: Datatypes and performance

From: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
To: Maksim Likharev <mlikharev(at)aurigin(dot)com>
Cc: PostgreSQL List <pgsql-general(at)postgresql(dot)org>
Subject: Re: Datatypes and performance
Date: 2003-07-04 21:54:08
Message-ID: 20030704215408.GB21432@dcc.uchile.cl
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On Fri, Jul 04, 2003 at 02:22:39PM -0700, Maksim Likharev wrote:
> Ok, what I see here tells me that text is slower then fixed len varchar,
> due to stored in separate table ( but how else you can store long fields
> ).
> so postgres has to read another page(s) in order to get long value.

That's regardless of the datatype: a varchar longer than 2 KiB IIRC will
be stored in a separate table, just as a text longer than 2 KiB.
There's no difference _at all_ for those two datatypes _except_ that the
former is checked for maximum length. If you store 256 chars in a TEXT
field it will be in the main table as it were a varchar(256).

--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"Nunca confiaré en un traidor. Ni siquiera si el traidor lo he creado yo"
(Barón Vladimir Harkonnen)

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