pg_catalog.pg_get_serial_sequence() returns NULL

On Jun 26, 2007, at 10:28 AM, Sergey Karin wrote:

I use PG 8.1.5

I execute in psql next comands:

create table t_table (gid serial, name varchar);

select pg_catalog.pg_get_serial_sequence('t_table', 'gid');
pg_get_serial_sequence
------------------------
public.t_table_gid_seq

create table t_table_1() inherits (t_table);

\d t_table_1
Table "public.t_table_1"
column |       Type        |                     Модификаторы
---------+------------------- 
+-------------------------------------------------------
gid     | integer           | not null default nextval 
('t_table_gid_seq'::regclass)
name    | character varying |
Inherit: t_table

select pg_catalog.pg_get_serial_sequence('t_table_1', 'gid');
pg_get_serial_sequence
------------------------
<NULL>

The issue is that t_table_1.gid isn't actually a SERIAL column...
it's an int that pulls a default value from the t_table_gid_seq
sequence. Note that that sequence is the one defined for t_table.

In this case for right now you're stuck hard-coding the sequence name
in, or referring to the parent table :(.

How I can get name of sequence used by gid column of partition
table? And why for t_table_1 pg_get_serial_sequence() returns NULL?
It returns NULL also if I create new sequence manually and use
ALTER TABLE ALTER COLUMN <column> SET DEFAULT nextval
(<my_new_sequence>::regclass).

In http://www.postgresql.org/docs/8.1/static/datatype.html#DATATYPE-
SERIAL I can read that type SERIAL is equivalent to
CREATE SEQUENCE tablename_colname_seq;
CREATE TABLE tablename (
colname integer DEFAULT nextval('tablename_colname_seq') NOT NULL
);Thanks in advance

Sergey Karin

--
Jim Nasby jim@nasby.net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)