Обсуждение: text .vs. varchar

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text .vs. varchar

От
Joao Ferreira
Дата:
Hello all,

I have a big database in which much information is stored in TEXT type
columns (I did this initially because I did not want to limit the
maximum size of the string to be stored)... but...

.. let's say I choose an upper limit (p.ex. 200) for the string sizes
and I start a fresh database with VARCHAR(200).

What tradeoffs can I expect ? disk usage ? query execution times ?

thx
Joao



Re: text .vs. varchar

От
Bill Moran
Дата:
In response to Joao Ferreira <jmcferreira@critical-links.com>:

> Hello all,
>
> I have a big database in which much information is stored in TEXT type
> columns (I did this initially because I did not want to limit the
> maximum size of the string to be stored)... but...
>
> .. let's say I choose an upper limit (p.ex. 200) for the string sizes
> and I start a fresh database with VARCHAR(200).
>
> What tradeoffs can I expect ? disk usage ? query execution times ?

See the "Tip" on this page, it answers your questions:
http://www.postgresql.org/docs/8.3/static/datatype-character.html

--
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran@collaborativefusion.com
Phone: 412-422-3463x4023

Re: text .vs. varchar

От
Martin Gainty
Дата:
With Postgres appears that TEXT is preferred over varchar(N)
http://archives.postgresql.org/pgsql-general/2006-03/msg01522.php

Any other DB (e.g. Oracle) would suggest varchar as column only stores the length of the variable (variable character length..) vs any of the fixed length datatype(s)

Anyone else?
Martin
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> Date: Wed, 13 Aug 2008 08:45:19 -0400
> From: wmoran@collaborativefusion.com
> To: jmcferreira@critical-links.com
> CC: pgsql-general@postgresql.org
> Subject: Re: [GENERAL] text .vs. varchar
>
> In response to Joao Ferreira <jmcferreira@critical-links.com>:
>
> > Hello all,
> >
> > I have a big database in which much information is stored in TEXT type
> > columns (I did this initially because I did not want to limit the
> > maximum size of the string to be stored)... but...
> >
> > .. let's say I choose an upper limit (p.ex. 200) for the string sizes
> > and I start a fresh database with VARCHAR(200).
> >
> > What tradeoffs can I expect ? disk usage ? query execution times ?
>
> See the "Tip" on this page, it answers your questions:
> http://www.postgresql.org/docs/8.3/static/datatype-character.html
>
> --
> Bill Moran
> Collaborative Fusion Inc.
> http://people.collaborativefusion.com/~wmoran/
>
> wmoran@collaborativefusion.com
> Phone: 412-422-3463x4023
>
> --
> Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general


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Re: text .vs. varchar

От
Alvaro Herrera
Дата:
Martin Gainty wrote:

> With Postgres appears that TEXT is preferred over varchar(N)
> http://archives.postgresql.org/pgsql-general/2006-03/msg01522.php

Implementation-wise, they are exactly the same, modulo length checking.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.