On Mon, Sep 15, 2025 at 10:15 PM Masahiko Sawada <[email protected]> wrote: > > On Sun, Sep 14, 2025 at 7:55 PM Amit Kapila <[email protected]> wrote: > > > > On Fri, Sep 12, 2025 at 11:18 PM Masahiko Sawada <[email protected]> > > wrote: > > > > > > On Thu, Sep 11, 2025 at 9:08 PM Amit Kapila <[email protected]> > > > wrote: > > > > > > > > > > > For the shutdown sequence, can't we think of resetting effective_wal > > > > after a restart? > > > > > > Does it mean that effective_wal_level keeps 'logical' until the next > > > server starts? > > > > > > > Yes, IIUC, effective_wal_level is anyway a derived value based on > > current wal_level and presence of logical slots. So, what will be the > > impact if it is not accurate at shutdown? > > I think there won't be an impact at shutdown time. I would rather be > concerned that such behavior could confuse users. I think it would not > be a rare situation where users enable and disable logical decoding by > creating and dropping a temporary slot. If we keep effective_wal_level > 'logical' in this case, users would want to somehow disable logical > decoding as it could have a negative performance impact. >
When user is dropping a temporary slot, we should disable the decoding. The lazy behaviour should be for ERROR or session_exit cases. > There would > be two ways for users to change it to 'replica': restart the server or > create and drop a logical slot again. > If we do the lazy work during the checkpoint then they can perform the checkpoint command. On the other hand, for users who > dropped a non-temporary logical slot without an error or dropped the > non-last temporary slot, logical decoding is disabled without other > manual interventions. It could be pretty hard to assess the situation, > resulting in having users always checking effective_wal_level after > dropping a logical slot and doing extra steps to make the > effective_wal_level 'replica'. > When the last slot is dropped, anyway, users won't be able to perform any decoding. Do you mean that they want to know whether logical_wal is still being recorded? If so, then checking effective_wal_level would be the way. -- With Regards, Amit Kapila.
