On Tue, Apr 21, 2015 at 04:36:53PM -0400, Robert Haas wrote: > > Keep in mind there's a disconnect between dirtying a page and writing it > > to storage. A page could remain dirty for a long time in the buffer > > cache. This writing of sequential pages would occur at checkpoint time > > only, which seems the wrong thing to optimize. If some other process > > needs to evict pages to make room to read some other page in, surely > > it's going to try one page at a time, not write "many sequential dirty > > pages." > > Well, for a big sequential scan, we use a ring buffer, so we will > typically be evicting the pages that we ourselves read in moments > before. So in this case we would do a lot of sequential writes of > dirty pages.
Ah, yes, this again supports the prune-then-skip approach, rather than doing the first X% pruneable pages seen. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
