Re: Clarification on a Time travel feature
От
Hans-Juergen Schoenig
Тема
Re: Clarification on a Time travel feature
Дата
Msg-id
413B761A-192C-4E21-B451-CC556EF1DB24@cybertec.at
Ответ на
Clarification on a Time travel feature (Gokulakannan Somasundaram)
Список
Дерево обсуждения
Clarification on a Time travel feature "Gokulakannan Somasundaram" <gokul007@gmail.com>
Re: Clarification on a Time travel feature Hans-Juergen Schoenig <postgres@cybertec.at>
Re: Andrew Dunstan <andrew@dunslane.net>
Re: Michael Glaesemann <grzm@seespotcode.net>
Re: Clarification on a Time travel feature "Gokulakannan Somasundaram" <gokul007@gmail.com>
Re: Clarification on a Time travel feature Heikki Linnakangas <heikki@enterprisedb.com>
Re: Clarification on a Time travel feature "Gokulakannan Somasundaram" <gokul007@gmail.com>
Re: Clarification on a Time travel feature "Gokulakannan Somasundaram" <gokul007@gmail.com>
Re: Clarification on a Time travel feature "Gokulakannan Somasundaram" <gokul007@gmail.com>
Re: Clarification on a Time travel feature "Jonah H. Harris" <jonah.harris@gmail.com>
hello ...
i guess there is no formal proposal yet but there are some ideas around and some major challenges have been discussed already.
i think simon riggs was planning to work on it in the future.
the basic idea here is to have the option to create a "snapshot" which then stays in the database. the main challenge is that PostgreSQL
should not keep all version of a row since the snapshot but VACUUM should be able to clean out all rows which are not seen by any snapshot or any ongoing transaction.
this should be a quite fancy solution which is quite space efficient.
internally we had the idea of tweaking VACUUM a little:
VACUUM BEFORE timestamp;
and ...
SET current_snapshot TO '2007-10-10 ...';
this would allow a queries to use any snapshot after the timestamp defined by VACUUM (if data is around).
the downside here: you might potentially eat up more space.
flashback data should be read only, of course.
best regards,
hans
On Oct 31, 2007, at 11:31 AM, Gokulakannan Somasundaram wrote:
Hi,
I went through the mailing list and couldn't get answer to the question.
a) Is there a proposal in place for going back in time within a transaction?
--
Thanks,
Gokul.
CertoSQL Project,
Allied Solution Groups.
(www.alliedgroups.com)
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