On Wed, Jun 7, 2023 at 5:19 AM Drouvot, Bertrand <bertranddrouvot...@gmail.com> wrote: > > Hi, > > On 6/7/23 7:32 AM, Jaime Casanova wrote: > > > > So, I wonder if that function is really needed because as I said I > > solved it with already existing functionality. Or if it is really > > needed maybe it is a bug that a CHECKPOINT and pg_switch_wal() have > > the same effect? > > > > Even if CHECKPOINT and pg_switch_wal() do produce the same effect, I think > they are expensive (as compare to pg_log_standby_snapshot() which does > nothing but > emit a xl_running_xacts). > > For this reason, I think pg_log_standby_snapshot() is worth to have/keep. >
CHECKPOINT could be expensive in a busy system, but the problem pg_log_standby_snapshot() is solving is about a no-activity system, and in a no-activity system CHECKPOINT is very fast. Even with very low activity SUBSCRIPTION flows fine. As an example I put an INSERT happening every 10s and SUBSCRIPTION never stuck no CHECKPOINT nor pg_log_standby_snapshot() needed. -- Jaime Casanova Director de Servicios Profesionales SYSTEMGUARDS - Consultores de PostgreSQL
