On 2018-08-31 19:31:47 -0300, Alvaro Herrera wrote: > On 2018-Aug-31, David Pacheco wrote: > > > From reading the 9.6.3 source, it looks like the autovacuum process > > itself is single-threaded, and it reads pages essentially linearly > > from the relation (possibly skipping some). When the autovacuum > > process needs to modify a page, it doesn't write it directly, but > > rather marks the buffer dirty. The page will be written later, > > Unless there's some bug, there is a BufferAccessStrategy that only lets > a few dozen buffers go unwritten before the autovac worker process > itself is forced to write some. I've not re-checked, but I'm not sure that's true if the buffer is already in s_b, which it'll be for many workloads. Greetings, Andres Freund
