'Crash consistent' is a term I heard in some oracle white papers.. If I am correct, it means the database would be consistent after the crash recovery is done.
>> Which means it is consistent at the time that the pg_start_backup >> is run. >No. It will be consistent with the time that pg_stop_backup was >run, or any later point in time that you choose, as long as you >have WAL to that point in time. In the manual, we where told to do three steps: 1) pg_start_backup 2) backup by tar 3) pg_stop_backup If the backup is consistent when pg_stop_backup is called, I think it worth to mention it in the manual. Thanks and regards, Patrick Dung ________________________________ From: Kevin Grittner <kgri...@ymail.com> To: Patrick Dung <patrick_...@yahoo.com.hk>; Albe Laurenz <laurenz.a...@wien.gv.at>; "pgsql-admin@postgresql.org" <pgsql-admin@postgresql.org> Sent: Wednesday, August 28, 2013 3:31 AM Subject: Re: [ADMIN] several questions about pg_dumpall, pg_start_backup, pg_basebackup and WAL Patrick Dung <patrick_...@yahoo.com.hk> wrote: > Albe Laurenz <laurenz.a...@wien.gv.at> >> Patrick Dung wrote: >>> It is possible that there is file changes (added or file size >>> changed) between the pg_start_backup and pg_stop_backup. >> >> Yes. >> >>> Is the backup consistent? >> >> The tar or snapshot itself will not be consistent, it will have >> to be recovered at least until the end on the online backup. > > I should ask: is the backup crash consistent? PITR restore procedures will use the crash recovery mechanism to make the database consistent, if that's what you mean. > Which means it is consistent at the time that the pg_start_backup > is run. No. It will be consistent with the time that pg_stop_backup was run, or any later point in time that you choose, as long as you have WAL to that point in time. -- Kevin Grittner EDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
