Обсуждение: Rép. : Re: [HACKERS] Hot Backup
What I understood from the Administrator's guide is: - Yes, PostgreSQL provides hot backup: it's the pg_dump utility. It'h hot because users can still be connected and workwhil pg_dump is running ( though they will be slowed down). ( See Administrator's guide ch9) - No, PostgreSQL does NOT provide a way to restore a database up to the last commited transaction, with a reapply of theWAL, as Oracle or SQL Server ( and others, I guess) do. That would be a VERY good feature. See Administrator's guide ch11 So, with Pg, if you backup your db every night with pg_dump, and your server crashes during the day, you will loose up toone day of work. Am I true? Erwan ------------------------------------------------------------------------------- Erwan DUROSELLE // SEAFRANCE DSI Responsable Bases de Données // Databases Manager Tel: +33 (0)1 55 31 59 70 // Fax: +33 (0)1 55 31 85 28 email: eduroselle@seafrance.fr ------------------------------------------------------------------------------- >>> Neil Conway <neilc@samurai.com> 07/10/2002 19:48 >>> "Sandeep Chadha" <sandeep@newnetco.com> writes: > Postgresql has been lacking this all along. I've installed postgres > 7.3b2 and still don't see any archive's flushed to any other > place. Please let me know how is hot backup procedure implemented in > current 7.3 beta(2) release. AFAIK no such hot backup feature has been implemented for 7.3 -- you appear to have been misinformed. That said, I agree that would be a good feature to have. Cheers, Neil -- Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
On Tue, Oct 08, 2002 at 12:35:22PM +0200, Erwan DUROSELLE wrote: > What I understood from the Administrator's guide is: > > - Yes, PostgreSQL provides hot backup: it's the pg_dump utility. It'h > hot because users can still be connected and work whil pg_dump is running > ( though they will be slowed down). ( See Administrator's guide ch9) Correct. > - No, PostgreSQL does NOT provide a way to restore a database up to the > last commited transaction, with a reapply of the WAL, as Oracle or SQL > Server ( and others, I guess) do. That would be a VERY good feature. See > Administrator's guide ch11 Umm, I thought the whole point of WAL was that if the database crashed, the WAL would provide the info to replay to the last committed transaction. http://www.postgresql.org/idocs/index.php?wal.html ... because we know that in the event of a crash we will be able to recover the database using the log: ... These docs seem to corrobrate this. > So, with Pg, if you backup your db every night with pg_dump, and your > server crashes during the day, you will loose up to one day of work. I've never lost any data with postgres, even if it's crashed, even without WAL. -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > There are 10 kinds of people in the world, those that can do binary > arithmetic and those that can't.
Martijn! Tuesday, October 08, 2002, 3:45:13 PM, you wrote: >> - No, PostgreSQL does NOT provide a way to restore a database up to the >> last commited transaction, with a reapply of the WAL, as Oracle or SQL >> Server ( and others, I guess) do. That would be a VERY good feature. See >> Administrator's guide ch11 MvO> Umm, I thought the whole point of WAL was that if the database crashed, the MvO> WAL would provide the info to replay to the last committed transaction. MvO> http://www.postgresql.org/idocs/index.php?wal.html MvO> ... because we know that in the event of a crash we will be able to recover MvO> the database using the log: ... MvO> These docs seem to corrobrate this. >> So, with Pg, if you backup your db every night with pg_dump, and your >> server crashes during the day, you will loose up to one day of work. MvO> I've never lost any data with postgres, even if it's crashed, even without MvO> WAL. Suppose you made your nightly backup, and then after a day of work the building where your server is located disappears in flames.. That's it - you lost one day of work (of course, if your dumps where stored outside that building otherwise you lost everything).. There is a need in "incremental" backup, which backs up only those transactions which has been fulfilled after last "full dump" or last "incremental dump". These backups should be done quite painlessly - just copy some part of WAL, and should be small enough (compared to full dump), so they can be done each hour or even more frequently.. I hope sometime PostgreSQL will support that. :-) Sincerely Yours, Timur mailto:itvthor@sdf.lonestar.org