Re: Block level parallel vacuum WIP

On Tue, Aug 23, 2016 at 8:02 PM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> As for PoC, I implemented parallel vacuum so that each worker
> processes both 1 and 2 phases for particular block range.
> Suppose we vacuum 1000 blocks table with 4 workers, each worker
> processes 250 consecutive blocks in phase 1 and then reclaims dead
> tuples from heap and indexes (phase 2).

So each worker is assigned a range of blocks, and processes them in
parallel? This does not sound performance-wise. I recall Robert and
Amit emails on the matter for sequential scan that this would suck
performance out particularly for rotating disks.
-- 
Michael