On Mon, May 17, 2021 at 8:50 AM Kyotaro Horiguchi <horikyota....@gmail.com> wrote: > > Before the commit expectedTLEs is always initialized with just one > entry for the TLI of the last checkpoint record.
Right > (1) If XLogFileReadAnyTLI() found the segment but no history file > found, that is, using the dummy TLE-list, expectedTLEs is initialized > with the dummy one-entry list. So there's no behavioral change in this > aspect. Yeah, you are right. > (2) If we didn't find the segment for the checkpoint record, it starts > replication and fetches history files and WAL records then revisits > XLogFileReadAnyTLI. Now we have both the history file and segments, > it successfully reads the recood. The difference of expectedTLEs made > by the patch is having just one entry or the all entries for the past. Correct. > Assuming that we keep expectedTLEs synced with recoveryTargetTLI, > rescanLatestTimeLine updates the list properly so no need to worry > about the future. So the issue would be in the past timelines. After > reading the checkpoint record, if we need to rewind to the previous > timeline for the REDO point, the dummy list is inconvenient. > > So there is a possibility that the patch fixed the case (2), where the > standby doesn't have both the segment for the checkpoint record and > the history file for the checkpoint, and the REDO point is on the last > TLI. If it is correct, the patch still fails for the case (1), that > is, the issue raised here. Anyway it would be useless (and rahter > harmful) to initialize expectedTLEs based on receiveTLI there. > > So my resul there is: > > The commit fixed the case (2) Yes, by maintaining the entire history instead of one entry if history was missing. > The fix caused the issue for the case (1). Basically, before this commit expectedTLEs and recoveryTargetTLI were in always in sync which this patch broke. > The proposed fix fixes the case (1), caused by the commit. Right, I agree with the fix. So fix should be just to change that one line and initialize expectedTLEs from recoveryTargetTLI -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com
