On Mar 26, 2011, at 4:16 PM, Jan Wieck <janwi...@yahoo.com> wrote: > That was what I meant. Go in steps of 16-64MB backwards and scan from there > to the current end in forward direction to find a nondeletable block. In > between these steps, release and reacquire the exclusive lock so that client > transactions can get their work done.
Well, VACUUM uses a 16MB ring buffer, so anything that size or smaller should hit shared_buffers most of the time. I wonder though if this might defeat read-behind on operating systems that do have a working implementation. With our current approach each read will end at the point the previous read started, which might be an algorithm somebody is using to detect a backward scan. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
