On Aug 19, 2013, at 9:11 PM, Andres Freund wrote: > On 2013-08-19 20:15:51 +0200, Boszormenyi Zoltan wrote: >> 2013-08-19 19:20 keltezéssel, Andres Freund írta: >>> Hi, >>> >>> On 2013-07-24 09:20:52 +0200, Antonin Houska wrote: >>>> Hello, >>>> the purpose of this patch is to limit impact of pg_backup on running >>>> server. >>>> Feedback is appreciated. >>> Based on a quick look it seems like you're throttling on the receiving >>> side. Is that a good idea? Especially over longer latency links, TCP >>> buffering will reduce the effect on the sender side considerably. > >> Throttling on the sender side requires extending the syntax of >> BASE_BACKUP and maybe START_REPLICATION so both can be >> throttled but throttling is still initiated by the receiver side. > > Seems fine to me. Under the premise that the idea is decided to be > worthwile to be integrated. Which I am not yet convinced of.
i think there is a lot of value for this one. the scenario we had a couple of times is pretty simple: just assume a weak server - maybe just one disk or two - and a slave. master and slave are connected via a 1 GB network. pg_basebackup will fetch data full speed basically putting those lonely disks out of business. we actually had a case where a client asked if "PostgreSQL is locked during base backup". of course it was just disk wait caused by a full speed pg_basebackup. regarding the client side implementation: we have chosen this way because it is less invasive. i cannot see a reason to do this on the server side because we won't have 10 pg_basebackup-style tools making use of this feature anyway. of course, if you got 20 disk and a 1 gbit network this is useless - but many people don't have that. regards, hans-jürgen schönig -- Cybertec Schönig & Schönig GmbH Gröhrmühlgasse 26 A-2700 Wiener Neustadt, Austria Web: http://www.postgresql-support.de -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers