On Mon, 23 Dec 2019 at 19:41, Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Fri, Dec 20, 2019 at 12:13 PM Masahiko Sawada > <masahiko.saw...@2ndquadrant.com> wrote: > > > > I've attached the updated version patch that incorporated the all > > review comments I go so far. > > > > I have further edited the first two patches posted by you. The > changes include (a) changed tests to reset the guc, (b) removing some > stuff which is not required in this version, (c) moving some variables > around to make them in better order, (d) changed comments and few > other cosmetic things and (e) commit messages for first two patches. > > I think the first two patches attached in this email are in good shape > and we can commit those unless you or someone has more comments on > them, the main parallel vacuum patch can still be improved by some > more test/polish/review. I am planning to push the first two patches > next week after another pass. The first two patches are explained in > brief as below: > > 1. v4-0001-Delete-empty-pages-in-each-pass-during-GIST-VACUUM: It > allows us to delete empty pages in each pass during GIST VACUUM. > Earlier, we use to postpone deleting empty pages till the second stage > of vacuum to amortize the cost of scanning internal pages. However, > that can sometimes (say vacuum is canceled or errored between first > and second stage) delay the pages to be recycled. Another thing is > that to facilitate deleting empty pages in the second stage, we need > to share the information of internal and empty pages between different > stages of vacuum. It will be quite tricky to share this information > via DSM which is required for the main parallel vacuum patch. Also, > it will bring the logic to reclaim deleted pages closer to nbtree > where we delete empty pages in each pass. Overall, the advantages of > deleting empty pages in each pass outweigh the advantages of > postponing the same. This patch is discussed in detail in a separate > thread [1]. > > 2. v39-0001-Introduce-IndexAM-fields-for-parallel-vacuum.patch: > Introduce new fields amusemaintenanceworkmem and > amparallelvacuumoptions in IndexAmRoutine for parallel vacuum. The > amusemaintenanceworkmem tells whether a particular IndexAM uses > maintenance_work_mem or not. This will help in controlling the memory > used by individual workers as otherwise, each worker can consume > memory equal to maintenance_work_mem. This has been discussed in > detail in a separate thread as well [2]. The amparallelvacuumoptions > tell whether a particular IndexAM participates in a parallel vacuum > and if so in which phase (bulkdelete, vacuumcleanup) of vacuum. > >
Thank you for updating the patches! The first patches look good to me. I'm reviewing other patches and will post comments if there is. Regards, -- Masahiko Sawada http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
