2011/1/5 Magnus Hagander <mag...@hagander.net>: > On Wed, Jan 5, 2011 at 22:58, Dimitri Fontaine <dimi...@2ndquadrant.fr> wrote: >> Magnus Hagander <mag...@hagander.net> writes: >>> * Stefan mentiond it might be useful to put some >>> posix_fadvise(POSIX_FADV_DONTNEED) >>> in the process that streams all the files out. Seems useful, as long as >>> that >>> doesn't kick them out of the cache *completely*, for other backends as >>> well. >>> Do we know if that is the case? >> >> Maybe have a look at pgfincore to only tag DONTNEED for blocks that are >> not already in SHM? > > I think that's way more complex than we want to go here. >
DONTNEED will remove the block from OS buffer everytime. It should not be that hard to implement a snapshot(it needs mincore()) and to restore previous state. I don't know how basebackup is performed exactly...so perhaps I am wrong. posix_fadvise support is already in postgresql core...we can start by just doing a snapshot of the files before starting, or at some point in the basebackup, it will need only 256kB per GB of data... -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
