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* pg_attribute.attlen -1 for varchar e pbchar fields
@ 2005-06-27 17:27 jimmy.olsen <jimmy.olsen@ig.com.br>
2005-06-27 20:35 ` Re: pg_attribute.attlen -1 for varchar e pbchar fields Michael Fuhr <mike@fuhr.org>
0 siblings, 1 reply; 2+ messages in thread
From: jimmy.olsen @ 2005-06-27 17:27 UTC (permalink / raw)
To: pgsql-sql
Hi listers,
I'm facing a problem getting information from meta tables. The command:
SELECT attname, atttypid, attlen
FROM pg_attribute
where atttypid IN(1042, 1043)
The attlen column always returns -1 for bpchar and varchar columns. the
postgre version is 8.0.1. When I look the tables in pgAdmin the column
lengths are correct. Where can I find the correct column lengths??
Alessandro - Liga One Sistemas
alessandro@ligaone.com.br
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: pg_attribute.attlen -1 for varchar e pbchar fields
2005-06-27 17:27 pg_attribute.attlen -1 for varchar e pbchar fields jimmy.olsen <jimmy.olsen@ig.com.br>
@ 2005-06-27 20:35 ` Michael Fuhr <mike@fuhr.org>
0 siblings, 0 replies; 2+ messages in thread
From: Michael Fuhr @ 2005-06-27 20:35 UTC (permalink / raw)
To: jimmy.olsen <jimmy.olsen@ig.com.br>; +Cc: pgsql-sql
On Mon, Jun 27, 2005 at 02:27:41PM -0300, jimmy.olsen wrote:
>
> SELECT attname, atttypid, attlen
> FROM pg_attribute
> where atttypid IN(1042, 1043)
>
> The attlen column always returns -1 for bpchar and varchar columns. the
> postgre version is 8.0.1. When I look the tables in pgAdmin the column
> lengths are correct. Where can I find the correct column lengths??
See the atttypmod column or the format_type() function:
CREATE TABLE foo (
col_char_1 char(1),
col_char_5 char(5),
col_varchar_10 varchar(10),
col_text text
);
SELECT attname, attlen, atttypmod, format_type(atttypid, atttypmod)
FROM pg_attribute
WHERE attrelid = 'foo'::regclass AND attnum > 0;
attname | attlen | atttypmod | format_type
----------------+--------+-----------+-----------------------
col_char_1 | -1 | 5 | character(1)
col_char_5 | -1 | 9 | character(5)
col_varchar_10 | -1 | 14 | character varying(10)
col_text | -1 | -1 | text
(4 rows)
Notice that atttypmod is 4 greater than the declared length;
presumably the difference is due to the varlena header (the 32-bit
integer that stores the data length). However, that's getting a
little close to internals, so you might want to stick with calling
format_type().
BTW, it's "PostgreSQL" or "Postgres," not "Postgre."
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/
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2005-06-27 17:27 pg_attribute.attlen -1 for varchar e pbchar fields jimmy.olsen <jimmy.olsen@ig.com.br>
2005-06-27 20:35 ` Michael Fuhr <mike@fuhr.org>
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