On Fri, Jan 8, 2021 at 2:19 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > The system header change has one interesting consequence for existing > releases of PostgreSQL, though: xlogdefs.h now sees that there is an > O_DSYNC macro that is distinct from O_SYNC, and defaults to > wal_sync_method=open_datasync. That's not a great default setting, > because it gets you O_DIRECT | O_DSYNC, which performs terribly when > you're writing 8KB blocks on UFS's default 32KB logical block size (it > triggers read-before-write, quite visibly destroying performance with > eg pg_test_fsync), and for all I know, it might even not work at all > on some other file systems. I suspect it might come out very slightly > ahead on a UFS filesystem created with 8KB blocks, but in any case, > that seems like something you should have to opt in to, as you do on > Linux.
Done.
