Re: Synchronizing slots from primary to standby

On Mon, Nov 6, 2023 at 1:57 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Mon, Nov 6, 2023 at 7:01 AM Zhijie Hou (Fujitsu)
> <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> >

+static void
+WalSndGetStandbySlots(List **standby_slots, bool force)
+{
+ if (!MyReplicationSlot->data.failover)
+ return;
+
+ if (standby_slot_names_list == NIL && strcmp(standby_slot_names, "") != 0)
+ SlotSyncInitConfig();
+
+ if (force || StandbySlotNamesPreReload == NULL ||
+ strcmp(StandbySlotNamesPreReload, standby_slot_names) != 0)
+ {
+ list_free(*standby_slots);
+
+ if (StandbySlotNamesPreReload)
+ pfree(StandbySlotNamesPreReload);
+
+ StandbySlotNamesPreReload = pstrdup(standby_slot_names);
+ *standby_slots = list_copy(standby_slot_names_list);
+ }
+}

I find this code bit difficult to understand. I think we don't need to
maintain a global variable like StandbySlotNamesPreReload. We can use
a local variable for it on the lines of what we do in
StartupRereadConfig(). Then, can we think of maintaining
standby_slot_names_list in something related to decoding like
LogicalDecodingContext as this will be used during decoding only?

--
With Regards,
Amit Kapila.