On Tue, Nov 28, 2023 at 2:17 PM Drouvot, Bertrand <bertranddrouvot...@gmail.com> wrote: > > On 11/2/23 1:27 AM, Zhijie Hou (Fujitsu) wrote: > > On Tuesday, October 31, 2023 6:45 PM Amit Kapila <amit.kapil...@gmail.com> > > wrote: > >> We have create_replication_slot and drop_replication_slot in repl_gram.y. > >> How > >> about if introduce alter_replication_slot and handle the 'failover' flag > >> with that? > >> The idea is we will either enable 'failover' at the time > >> create_replication_slot by > >> providing an optional failover option or execute a separate command > >> alter_replication_slot. I think we probably need to perform this command > >> before the start of streaming. > > > > Here is an attempt to achieve the same. I added a new replication command > > alter_replication_slot and introduced a walreceiver api walrcv_alter_slot to > > execute the command. The subscription will call the api to enable/disable > > the failover of the slot on publisher. > > > > The patch disallows altering the failover option for the subscription. But > > we > > could release the restriction by using the following approaches in next > > version: > > > >> I think we will have the following options to allow alter of the 'failover' > >> property: (a) we can allow altering 'failover' only for the 'disabled' > >> subscription; to achieve that, we need to open a connection during alter > >> subscription and change this property of slot; (b) apply worker detects the > >> change in 'failover' option; run the alter_replication_slot command; this > >> needs > >> more analysis as apply_worker is already doing streaming and changing slot > >> property in between could be tricky. > > > > What do you think about also adding a pg_alter_logical_replication_slot() or > such > function? > > That would allow users to alter manually created logical replication slots > without > the need to make a replication connection. >
But then won't that make it inconsistent with the subscription failover state? I think if we don't have a simple solution for this, we can always do it as an enhancement to the main feature once we have good ideas to solve it. -- With Regards, Amit Kapila.
