The following bug has been logged online:

Bug reference: 2336
Logged by: Chris Mair
Email address: chris@1006.org
PostgreSQL version: 8.1.3
Operating system: MacOS X 10.3.9
Description: will not drop implicitly created sequence
Details:

Ok, so this is probably not a bug at all - just slightly unexpected
behaviour.

This piece of SQL:
---------------------------------------------------
create table test2 (id serial, txt varchar);
-- (will create implicit sequence "test2_id_seq")
alter table test2 alter id set default 123;
drop sequence test2_id_seq;
---------------------------------------------------

would say:
---------------------------------------------------
ERROR: 2BP01: cannot drop sequence test2_id_seq because table test2 column
id requires it
HINT: You may drop table test2 column id instead.
LOCATION: recursiveDeletion, dependency.c:472
---------------------------------------------------

as if test2.id would still use the sequence.

Contrast this with the same thing done with an explicitly declared
sequence:
---------------------------------------------------
create sequence test1_id_seq;
create table test1 (id int not null default nextval('test1_id_seq'), txt
varchar);
alter table test1 alter id set default 123;
drop sequence test1_id_seq;
---------------------------------------------------

which will just work fine.

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TODO has:

* %Disallow changing default expression of a SERIAL column

so we know it is a bug.

---------------------------------------------------------------------------

Chris Mair wrote:
>
> The following bug has been logged online:
>
> Bug reference: 2336
> Logged by: Chris Mair
> Email address: chris@1006.org
> PostgreSQL version: 8.1.3
> Operating system: MacOS X 10.3.9
> Description: will not drop implicitly created sequence
> Details:
>
> Ok, so this is probably not a bug at all - just slightly unexpected
> behaviour.
>
> This piece of SQL:
> ---------------------------------------------------
> create table test2 (id serial, txt varchar);
> -- (will create implicit sequence "test2_id_seq")
> alter table test2 alter id set default 123;
> drop sequence test2_id_seq;
> ---------------------------------------------------
>
> would say:
> ---------------------------------------------------
> ERROR: 2BP01: cannot drop sequence test2_id_seq because table test2 column
> id requires it
> HINT: You may drop table test2 column id instead.
> LOCATION: recursiveDeletion, dependency.c:472
> ---------------------------------------------------
>
> as if test2.id would still use the sequence.
>
> Contrast this with the same thing done with an explicitly declared
> sequence:
> ---------------------------------------------------
> create sequence test1_id_seq;
> create table test1 (id int not null default nextval('test1_id_seq'), txt
> varchar);
> alter table test1 alter id set default 123;
> drop sequence test1_id_seq;
> ---------------------------------------------------
>
> which will just work fine.
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
>
> http://archives.postgresql.org
>

--
Bruce Momjian http://candle.pha.pa.us
SRA OSS, Inc. http://www.sraoss.com

+ If your life is a hard drive, Christ can be your backup. +

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