On Tue, Jan 10, 2017 at 6:42 AM, Masahiko Sawada <sawada.m...@gmail.com> wrote: >> Does this work negate the other work to allow VACUUM to use > >> 1GB memory? > > Partly yes. Because memory space for dead TIDs needs to be allocated > in DSM before vacuum worker launches, parallel lazy vacuum cannot use > such a variable amount of memory as that work does. But in > non-parallel lazy vacuum, that work would be effective. We might be > able to do similar thing using DSA but I'm not sure that is better.
I think it would work well with DSA as well. Just instead of having a single segment list, you'd have one per worker. Since workers work on disjoint tid sets, that shouldn't pose a problem. The segment list can be joined together later rather efficiently (simple logical joining of the segment pointer arrays) for the index scan phases. -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers