On Mon, Nov 30, 2009 at 4:56 AM, Boszormenyi Zoltan <z...@cybertec.at> wrote: > I don't think its reasonable trying to discuss and implement this all > in one huge patch so I propose implementing at least 1) as a seperate > patch.
I agree with this development plan. > Now there unforatunately are two different schools of thought how to > implement transfering base data. > 1. archive_command like transfer command taking a source path/host and target > path/host > - very flexible (think e.g. not transferring the data for multiple slaves > over the whole country) > - harder to setup > - more in style of classical wal archiving > 2. add the capability to the WAL Streaming patch's libpq based protocol > - no additional configuration needed > - inflexible > - makes usage from non streaming replication is impossible > > I favor 1. but only lightly so. I favor 2 ;) Because I think that it's too hard for users to set up a transfer command. One of streaming replication's merits is that users no longer need to specify a transfer command for log-shipping. So users can configure and use replication without complex settings. But, #1 would spoil this merit. > Detail Questions: > - How to deal with multiple transfer requests at the same time? > There would be a need for multiple full backup requests for > individual tables by several clients at once. > Currently pg_start_backup() isn't allowed from > two clients in parallel, the second one gets an error. > We thought that pg_start_backup() and pg_stop_backup() > can turn into simple reference counts. IIRC, WALs > are still generated and _shipped to slaves_ during > a full backup, they are simply not yet applied to > base table files. So, in this case a pg_stop_backup() > issued from a slave decreases refcount of the base backups > and the slave can simply resume applying its newly > received WALs to base files. I'm not sure how. But at first multiple online-backup feature rather than backup-shipping itself might have to be addressed. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
