At Tue, 10 Nov 2020 09:33:12 -0500, Stephen Frost <sfr...@snowman.net> wrote in > Greetings, > > * Kyotaro Horiguchi (horikyota....@gmail.com) wrote: > > For fuel(?) of the discussion, I tried a very-quick PoC for in-place > > ALTER TABLE SET LOGGED/UNLOGGED and resulted as attached. After some > > trials of several ways, I drifted to the following way after poking > > several ways. > > > > 1. Flip BM_PERMANENT of active buffers > > 2. adding/removing init fork > > 3. sync files, > > 4. Flip pg_class.relpersistence. > > > > It always skips table copy in the SET UNLOGGED case, and only when > > wal_level=minimal in the SET LOGGED case. Crash recovery seems > > working by some brief testing by hand. > > Somehow missed that this patch more-or-less does what I was referring to > down-thread, but I did want to mention that it looks like it's missing a > necessary FlushRelationBuffers() call before the sync, otherwise there > could be dirty buffers for the relation that's being set to LOGGED (with > wal_level=minimal), which wouldn't be good. See the comments above > smgrimmedsync(). > > > Of course, I haven't performed intensive test on it. > > Reading through the thread, it didn't seem very clear, but we should > definitely make sure that it does the right thing on replicas when going > between unlogged and logged (and between logged and unlogged too), of > course. > > Thanks,
Thanks! Since this feature is different from the feature that is being proposed in this thhead, I started another thread for this feature. https://www.postgresql.org/message-id/20201111.173317.460890039962481381.horikyota....@gmail.com regards. -- Kyotaro Horiguchi NTT Open Source Software Center
