On 9/12/16 11:16 PM, Michael Paquier wrote: >> I don't think tar file output in pg_basebackup needs to be fsynced. >> > It's just a backup file like what pg_dump produces, and we don't fsync >> > that either. The point of this change is to leave a data directory in >> > a synced state equivalent to what initdb leaves behind. > Here I don't agree. The point of the patch is to make sure that what > gets generated by pg_basebackup is consistent on disk, for all the > formats. It seems weird to me that we could say that the plain format > makes things consistent while the tar format may cause some files to > be lost in case of power outage. The docs make it clear I think: > + By default, <command>pg_basebackup</command> will wait for all files > + to be written safely to disk. > But perhaps this should directly mention that this is done for all the > formats?
That doesn't really explain why we fsync. If we think that all "important" files should be fsynced, why aren't we doing it in pg_dump? Or psql, or server-side copy? Similarly, there is no straightforward mechanism by which you can unpack the tar file generated by pg_basebackup and get the unpacked directory fsynced properly. (I suppose initdb -S should be recommended.) -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers