On Fri, Oct 27, 2023 at 4:04 PM shveta malik <shveta.ma...@gmail.com> wrote: > > On Fri, Oct 27, 2023 at 3:26 PM shveta malik <shveta.ma...@gmail.com> wrote: > ========== > > Open questions regarding change for pt 1 above: > a) I think we should restrict the 'alter-sub set failover' when > failover-state is currently in 'p' (pending) state i.e. table-sync is > going over. Once table-sync is over, then toggle of 'failover' should > be allowed using alter-subscription. >
Agreed. > b) Currently I have restricted 'alter subscription.. refresh > publication with copy=true' when failover=true (on a similar line of > two-phase). The reason being, refresh with copy=true will go for > table-sync again and since failover was set in main-slot after > table-sync was done, it will need going through the same transition of > 'p' to 'e' for main slot making it unsyncable for that time. Should it > be allowed? > Yeah, I also think we can't allow refresh with copy=true when 'failover' is enabled. I think the current implementation of this flag seems a bit clumsy because 'failover' is a slot property and we are trying to map it to plugin_options. It has to be considered similar to the opt_temporary option while creating the slot. 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. 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. -- With Regards, Amit Kapila.
