On Tue, Jan 4, 2022 at 9:00 AM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > According to the doc, the two_phase field has: > > True if the slot is enabled for decoding prepared transactions. Always > false for physical slots. > > It's unnatural a bit to me that replication slots have such a property > since the replication slots have been used to protect WAL and tuples > that are required for logical decoding, physical replication, and > backup, etc from removal. Also, it seems that even if a replication > slot is created with two_phase = off, it's overwritten to on if the > plugin enables two-phase option. Is there any reason why we can turn > on and off this value on the replication slot side and is there any > use case where the replication slot’s two_phase is false and the > plugin’s two-phase option is on and vice versa? >
We enable two_phase only when we start streaming from the subscriber-side. This is required because we can't enable it till the initial sync is complete, otherwise, it could lead to loss of data. See comments atop worker.c (description under the title: TWO_PHASE TRANSACTIONS). > I think that we can > have replication slots always have two_phase_at value and remove the > two_phase field from the view. > I am not sure how that will work because we can allow streaming of prepared transactions when the same is enabled at the CREATE SUBSCRIPTION time, the default for which is false. -- With Regards, Amit Kapila.
