Обсуждение: pgsql: Use the newest to-be-frozen xid as the conflict horizon for free
Use the newest to-be-frozen xid as the conflict horizon for freezing Previously WAL records that froze tuples used OldestXmin as the snapshot conflict horizon, or the visibility cutoff if the page would become all-frozen. Both are newer than (or equal to) the newst XID actually frozen on the page. Track the newest XID that will be frozen and use that as the snapshot conflict horizon instead. This yields an older horizon resulting in fewer query cancellations on standbys. Author: Melanie Plageman <melanieplageman@gmail.com> Reviewed-by: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/CAAKRu_bbaUV8OUjAfVa_iALgKnTSfB4gO3jnkfpcFgrxEpSGJQ%40mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/c2a23dcf9e3af1c80a99b4ee43f0885eb6894e3a Modified Files -------------- src/backend/access/heap/heapam.c | 14 ++++++++++++++ src/backend/access/heap/pruneheap.c | 36 +++++++++++------------------------- src/include/access/heapam.h | 12 ++++++++++++ 3 files changed, 37 insertions(+), 25 deletions(-)