Re: "ownership" of sequences, pseudo random unique id - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: "ownership" of sequences, pseudo random unique id
Date
Msg-id 20090820183102.GJ6261@alvh.no-ip.org
Whole thread Raw
In response to "ownership" of sequences, pseudo random unique id  (Ivan Sergio Borgonovo <mail@webthatworks.it>)
Responses Re: "ownership" of sequences, pseudo random unique id
List pgsql-general
Ivan Sergio Borgonovo wrote:
> I've
>
> create table pr(
>   code varchar(16) primary key,
>   ...
> );
> create sequence pr_code_seq owned by pr.code; -- uh!
>
> pr.code will *mostly* be obtained as
>
> to_hex(feistel_encrypt(nextval('pr_code')))
> and sometimes 'manually' inserting unique codes.
>
> actually stuff like:
> alter table pr drop column code;
> or just
> drop table pr
>
> seems to work as expected (they drop the sequence too).
>
> Should I be concerned of anything since it looks like a hack?

You need to ensure you have a retry loop in your insertion code, because
if the generated code conflicts with a manually inserted code, it will
cause an error.  Other than that, seems like it should work ...

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

pgsql-general by date:

Previous
From: Jeff Davis
Date:
Subject: Re: unique index for periods
Next
From: "Chris Hopkins"
Date:
Subject: Out of memory on pg_dump