Add nbtree README note on index-only scans in recovery. The nbtree README has long claimed that "the interlocking required to avoid returning incorrect results from non-MVCC scans is not required on standby nodes". A recent test case proved that the underlying reasoning was faulty.
There are significant practical challenges around fixing this bug, and no user has complained about it so far. The old "pin scan" mechanism prevented the problem but performed very poorly. Since there seems to be no appetite for resurrecting that mechanism, and since an acceptable fix hasn't been forthcoming, make a note of the issue for later. Discussion: https://postgr.es/m/cah2-wzkro678xedorsxrq-ydvp4w7nxybhvjv2mxrztj-5o...@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/9e7d152488f197e96f171f0714459c227c3f7693 Modified Files -------------- src/backend/access/nbtree/README | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
