Hello all and Heikki personally
Thank you for your answer I have some new points: Понедельник, 21 января 2013, 10:08 +02:00 от Heikki Linnakangas <hlinnakan...@vmware.com>: >On 21.01.2013 09:14, Миша Тюрин wrote: >> Is there any reason why pg_basebackup has limitation in an online backup >> from the standby: "The backup history file is not created in the database >> cluster backed up." ? > >WAL archiving isn't active in a standby, so even if it created a backup >history file, it wouldn't go anywhere. Also, the way the backup history >files are named, if you take a backup on the master at the same time (or >another backup at the same time in the standby), you would end up with >multiple backup history files with the same name. > >> So i can't get last xlog file needed to restore :( > >Good point. That was an oversight in the patch that allowed base backups >from a standby. > >> Also maybe i can use something like ( pg_last_xlog_replay_location() + 1 >> ) after pg_basebackup finished. > >Yeah, that should work. > >> Does anybody know true way to getting last xlog file in case of applying >> pg_basebackup to standby? >> How pg_basebackup gets last xlog file in case of standby and -x option? > >The server returns the begin and end WAL locations to pg_basebackup, >pg_basebackup just doesn't normally print them out to the user. In >verbose mode, it does actually print them out, but only with -x, so that >doesn't help you either. If you can compile from source, you could >modify pg_basebackup.c to print the locations without -x and --verbose, >search lines that print out "transaction log start point / end position". 1) we can get last xlog by using control data's "Minimum recovery ending location" > > >As a workaround, without modifying the source, you can do this after >pg_basebackup has finished, to get the first WAL file you need: > >$ pg_controldata backupdir | grep "REDO WAL file" >Latest checkpoint's REDO WAL file: 000000030000000000000009 and I would like to correct your suggestion about first wal file 2.1) we should use backup_label to determine first needed wal 2.2) and we must not use redo from checkpoint. because there are might be more than one checkpoint during base_backup > >And as you suggested, pg_last_xlog_replay_location() for the last WAL >file you need. > >- Heikki > > >-- >Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) >To make changes to your subscription: >http://www.postgresql.org/mailpref/pgsql-hackers - Misha
