On 8/23/21, 9:33 AM, "alvhe...@alvh.no-ip.org" <alvhe...@alvh.no-ip.org> wrote: > On 2021-Aug-23, Bossart, Nathan wrote: > >> Hm. My expectation would be that if there are no registrations, we >> cannot create .ready files for the flushed segments. The scenario >> where I can see that happening is when a record gets flushed to disk >> prior to registration. In that case, we'll still eventually register >> the record and wake up the WAL writer process, which will take care of >> creating the .ready files that were missed earlier. Is there another >> case you are thinking of where we could miss registration for a cross- >> segment record altogether? > > I'm thinking of the case where no record cross segment boundaries ever.
Sorry, I'm still not following this one. If we skipped creating .ready segments due to a crash, we rely on RemoveOldXlogFiles() to create them as needed in the end-of-recovery checkpoint. If a record fits perfectly in the end of a segment, we'll still register it as a boundary for the next segment (hence why we use XLByteToSeg() instead of XLByteToPrevSeg()). If database activity stops completely, there shouldn't be anything to mark ready. Nathan
