From: | Oleg Bartunov <oleg(at)sai(dot)msu(dot)su> |
---|---|
To: | Richard Huxton <dev(at)archonet(dot)com> |
Cc: | David Pradier <dpradier(at)apartia(dot)fr>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: How to add an INHERITS to an already populated table |
Date: | 2005-05-31 12:53:46 |
Message-ID: | Pine.GSO.4.62.0505311649130.16737@ra.sai.msu.su |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
On Tue, 31 May 2005, Oleg Bartunov wrote:
> look on pg_inherits table and pg_class.relhassubclass.
> More info http://www.pgsql.ru/db/mw/msg.html?mid=2044343
>
example:
create table t (i int4);
create table t1 (i int4);
create table t2 (i int4);
-- mark 't' has children tables
update pg_class set relhassubclass='t' where relname='t';
-- get oid of child table 't1'
select relfilenode from pg_class where relname='t1';
-- get oid of parent table
select relfilenode from pg_class where relname='t';
-- add inheritance t-t1
insert into pg_inherits values(15769046,15769044,1);
-- get oid of child table 't2'
select relfilenode from pg_class where relname='t2';
-- add inheritance t-t2
insert into pg_inherits values(15769048,15769044,1);
--test
test=# explain analyze select * from t;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------
Result (cost=0.00..88.20 rows=5820 width=8) (actual time=0.057..0.057 rows=0 loops=1)
-> Append (cost=0.00..88.20 rows=5820 width=8) (actual time=0.044..0.044 rows=0 loops=1)
-> Seq Scan on t (cost=0.00..29.40 rows=1940 width=8) (actual time=0.008..0.008 rows=0 loops=1)
-> Seq Scan on t1 t (cost=0.00..29.40 rows=1940 width=8) (actual time=0.007..0.007 rows=0 loops=1)
-> Seq Scan on t2 t (cost=0.00..29.40 rows=1940 width=8) (actual time=0.006..0.006 rows=0 loops=1)
Total runtime: 0.171 ms
(6 rows)
-- check if alter table works
alter table t add column x real;
test=# \d t
Table "public.t"
Column | Type | Modifiers
--------+---------+-----------
i | integer |
x | real |
test=# \d t1
Table "public.t1"
Column | Type | Modifiers
--------+---------+-----------
i | integer |
x | real |
Inherits: t
test=# \d t2
Table "public.t2"
Column | Type | Modifiers
--------+---------+-----------
i | integer |
x | real |
Inherits: t
>
> On Tue, 31 May 2005, Richard Huxton wrote:
>
>> David Pradier wrote:
>>> Hi everybody,
>>>
>>> is it possible to add some inheritance lively, without doing a
>>> dump/restore ?
>>
>> Not AFAIK. Easiest solution is probably to script some ALTER TABLE ADD
>> COLUMN commands.
>>
>>
>
> Regards,
> Oleg
> _____________________________________________________________
> Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
> Sternberg Astronomical Institute, Moscow University (Russia)
> Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
> phone: +007(095)939-16-83, +007(095)939-23-83
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq
>
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83
From | Date | Subject | |
---|---|---|---|
Next Message | FERREIRA, William (COFRAMI) | 2005-05-31 13:12:26 | database auto-commit |
Previous Message | Oleg Bartunov | 2005-05-31 12:33:39 | Re: How to add an INHERITS to an already populated table |