On Thu, Sep 30, 2021 at 11:32 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > I managed to produce a case where live data is written to an unlinked > file and lost
I guess this must have been broken since release 9.2 moved checkpoints out of here[1]. The connection between checkpoints, tombstone files and file descriptor cache invalidation in auxiliary (non-sinval) backends was not documented as far as I can see (or at least not anywhere near the load-bearing parts). How could it be fixed, simply and backpatchably? If BgSyncBuffer() did if-FirstCallSinceLastCheckpoint()-then-smgrcloseall() after locking each individual buffer and before flushing, then I think it might logically have the correct interlocking against relfilenode wraparound, but that sounds a tad expensive :-( I guess it could be made cheaper by using atomics for the checkpoint counter instead of spinlocks. Better ideas? [1] https://www.postgresql.org/message-id/flat/CA%2BU5nMLv2ah-HNHaQ%3D2rxhp_hDJ9jcf-LL2kW3sE4msfnUw9gA%40mail.gmail.com
