v1 rewound walrcv->flushedUpto in RequestXLogStreaming() whenever the
(segment-rounded) start pointer was behind it. That was too broad:
* RequestXLogStreaming() rounds recptr down to a segment boundary
before the comparison, so the rewind fired on ordinary reconnects,
not only after a failed read.
* pg_last_wal_receive_lsn() jumped backward.
* Cascading walsenders can hit Assert(sentPtr <= SendRqstPtr) when
GetStandbyFlushRecPtr() drops below a position they already sent.
* Kyotaro Horiguchi already argued against a blanket flushedUpto
rewind in 2021 [1].
v2 keeps flushedUpto monotonic. Startup uses a separate
applyFlushedUpto for "is this streamed WAL readable?". That pointer is
reset only after lastSourceFailed on archive/pg_wal, when the unrounded
restart LSN is still behind flushedUpto on the same timeline. Healthy
reconnects (including pendingWalRcvRestart after SIGHUP /
primary_conninfo change) keep the old apply pointer, so replay is not
stalled on WAL that is already on disk. After lastSourceFailed,
WaitForWALToBecomeAvailable() still tries archive/pg_wal first; the
reset only happens if those sources also fail.
The TAP test is now t/058_stream_repair.pl (053 and later numbers were
taken on current master). It checks both:
1. primary_conninfo reload with apply lag does not move
pg_last_wal_receive_lsn() backward.
2. A corrupt unreplayed record after receive has moved into the next
segment is replaced via streaming, instead of looping on the local
copy.
I have not re-run the recovery TAP suite against this tree (no local
install of current master).
[1]
https://postgr.es/m/20210329.105441.1978082841561262877.horikyota.ntt@gmail.com
Konstantin Knizhnik (1):
Keep flushedUpto monotonic; reset applyFlushedUpto after a failed
read.
src/backend/access/transam/xlogrecovery.c | 38 ++++-
src/backend/replication/walreceiver.c | 2 +
src/backend/replication/walreceiverfuncs.c | 45 +++++-
src/include/replication/walreceiver.h | 16 ++-
src/test/recovery/meson.build | 1 +
src/test/recovery/t/058_stream_repair.pl | 158 +++++++++++++++++++++
6 files changed, 255 insertions(+), 5 deletions(-)
create mode 100644 src/test/recovery/t/058_stream_repair.pl
