I've done more research and identified that replicas enter an indefinite loop in the 'XLogReadPage' function. The loop works as follows: 0. timeline N contains a partially written record with LSN = targetRecPtr; 1. In 'XLogReadPage' we attempt to read the next page, which has to contain the rest of the unfinished record; 2. In 'WaitForWALToBecomeAvailable' walrcv is requested to fetch records starting from LSN = targetRecPtr on timeline N + 1; 3. Walrcv retrieves data up to the end of page containing the end of timeline N + 1; 4. Then, in 'WaitForWALToBecomeAvailable', replica switches to XLOG_FROM_ARCHIVE state, and the function returns true; 5. Execution continues in 'XLogReadPage'; 6. The page at addr = targetPagePtr is checked for validity, but we get an 'invalid magic number' error because walrcv hasn't retrieved this page; 7. Execution jumps to 'next_record_is_invalid' label; 8. Since we are in StandBy mode, the process retries from the beginning.
See the attachments for more colorful illustration this time =)
From my point of view, the first solution which I described in my previous message still seems like a good choice.
I've also found the current solution in commit [1]. With all due respect, but it seems to treat the symptom rather than the underlying issue.
