Обсуждение: Display Length Between Var & Varchar

I've noticed when I set a field to char, it takes up lots of space over varchar:

iamunix=# SELECT * FROM music;id |       band        |          album           |    date    |                 asin
                  |    label
 

----+-------------------+--------------------------+------------+----------------------------------------------------+--------------
1| Dance Gavin Dance | Downtown Battle Mountain | 2007-05-15 |
 
B000OQF4PQ                                         | Rise Records
(1 row)

iamunix=# SELECT * FROM music;id |       band        |          album           |    date    |
asin    |    label
----+-------------------+--------------------------+------------+------------+-------------- 1 | Dance Gavin Dance |
DowntownBattle Mountain | 2007-05-15 |
 
B000OQF4PQ | Rise Records
(1 row)

I don't know how well it will show in plain text via email but does
anyone know why the field display width is wasted with so much white
space when set to char?

On Tuesday, January 31, 2012 8:08:06 pm Carlos Mennens wrote:
> I've noticed when I set a field to char, it takes up lots of space over
> varchar:
> 
> iamunix=# SELECT * FROM music;
>  id |       band        |          album           |    date    |
>                   asin                        |    label
> ----+-------------------+--------------------------+------------+----------
> ------------------------------------------+-------------- 1 | Dance Gavin
> Dance | Downtown Battle Mountain | 2007-05-15 |
> B000OQF4PQ                                         | Rise Records
> (1 row)
> 
> iamunix=# SELECT * FROM music;
>  id |       band        |          album           |    date    |
> asin    |    label
> ----+-------------------+--------------------------+------------+----------
> --+-------------- 1 | Dance Gavin Dance | Downtown Battle Mountain |
> 2007-05-15 |
> B000OQF4PQ | Rise Records
> (1 row)
> 
> I don't know how well it will show in plain text via email but does
> anyone know why the field display width is wasted with so much white
> space when set to char?

You will find that the Manual is very helpful in this regard:)

http://www.postgresql.org/docs/9.0/interactive/datatype-character.html
character varying(n), varchar(n)    variable-length with limit
character(n), char(n)    fixed-length, blank padded

-- 
Adrian Klaver
adrian.klaver@gmail.com