On Sun, May 7, 2023 at 10:18 PM Thomas Munro <thomas.mu...@gmail.com> wrote:
> On Mon, May 8, 2023 at 4:10 AM Evgeny Morozov > <postgres...@realityexists.net> wrote: > > On 6/05/2023 11:13 pm, Thomas Munro wrote: > > > Would you like to try requesting FILE_COPY for a while and see if it > eventually happens like that too? > > Sure, we can try that. > > Maybe you could do some one way and some the other, so that we try to > learn more? > > > Ubuntu 18.04.6 > > Kernel 4.15.0-206-generic #217-Ubuntu SMP Fri Feb 3 19:10:13 UTC 2023 > > x86_64 x86_64 x86_64 GNU/Linux > > zfsutils-linux package version 0.7.5-1ubuntu16.12 amd64 > > I tried for a few hours to reproduce this by trying to make as many > things as similar to yours as I could based on info in this thread > (Linux: up-to-date Ubuntu 18.04 in vagrant which has nearly the same > kernel 4.15.0-208-generic and a close but slightly different version > of ancient ZFS 0.7.5-1ubuntu15, not sure why, ZFS: mirror (I used a > pair of loopback files), recordsize=16kB, compression=lz4, PG: > compiled from tag REL_15_2, data_checksums=on, full_page_writes=off, > wal_recycle=off, wal_init_zero=off), with what I thought might be > roughly what you're doing (creating three DBs, two clones of the > first, with various modification at various points, with various > overlapping activities, and then checking for catalog corruption). No > cigar. Hrmph. > My first thought on this was along the lines of previous comments. We are writing the initial pieces of the files for a new DATABASE. Some flag is set, and then context is lost, and it ends up that a SAVE happens to an existing DATABASE. So, my thought was a parallel set of UPDATE "type" commands that would cause those types of pages for a stable/existing DB to be updated/written. It could be as simple as creating temp tables in the other database (since I believe pg_class was hit). >From a "rare" standpoint. That "feels" about right to me. It would pass serial tests (like you are running). Just a thought. Maybe a simple background script creating temp tables in another DB. Also, not sure if the OP has a set of things done after he creates the DB that may help? Kirk
