Re: Improve pg_sync_replication_slots() to wait for primary to advance - Mailing list pgsql-hackers

On Wed, Nov 12, 2025 at 1:54 PM Ajin Cherian <itsajin@gmail.com> wrote:
>
> Attaching patch v23 addressing these comments.
>

Few comments:
=============
1.
In contrast, automatic synchronization
       via <varname>sync_replication_slots</varname> provides continuous slot
       updates, enabling seamless failover and supporting high availability.
-      Therefore, it is the recommended method for synchronizing slots.

I think a slotsync worker should still be a recommended method. So, we
shouldn't remove the last line.

2. I think we can unify slotsync_api_reread_config() and
ProcessSlotSyncAPIInterrupts() with corresponding existing functions
for slotsync worker. Having separate functions for API and worker to
handle interrupts looks odd and bug-prone w.r.t future changes in this
area.

3.
+/*
+ * Helper function to extract slot names from a list of remote slots
+ */
+static List *
+extract_slot_names(List *remote_slots)
+{
+ List *slot_names = NIL;
+ MemoryContext oldcontext;
+
+ /* Switch to long-lived TopMemoryContext to store slot names */
+ oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+
+ foreach_ptr(RemoteSlot, remote_slot, remote_slots)

Why did we allocate this memory in TopMemoryContext here? We only need
till this function executes, isn't CurrentMemoryContext (which I think
is ExprContext) sufficient, if not, why? If we use some
function/query-level context then we don't need to make it part of
SlotSyncApiFailureParams. If we can get rid of slot_names from
SlotSyncApiFailureParams then we probably don't need struct
SlotSyncApiFailureParams.

--
With Regards,
Amit Kapila.