Re: Synchronizing slots from primary to standby

Hi Ajin. Thanks for addressing my previous review comments from v19.

I checked all the changes. Below are a few follow-up remarks.

On Thu, Oct 5, 2023 at 7:54 PM Ajin Cherian <itsajin(at)gmail(dot)com> wrote:
>
> On Wed, Sep 27, 2023 at 2:37 PM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
> >
> > Here are some more review comments for the patch v19-0002.

> > 3. get_local_synced_slot_names
> >
> > + for (int i = 0; i < max_replication_slots; i++)
> > + {
> > + ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
> > +
> > + /* Check if it is logical synchronized slot */
> > + if (s->in_use && SlotIsLogical(s) && s->data.synced)
> > + {
> > + for (int j = 0; j < MySlotSyncWorker->dbcount; j++)
> > + {
> >
> > Loop variables are not declared in the common PG code way.
> >
>
> fixed.

Yes, new declarations were added, but some of them (e.g. 'j') could
have been declared at a lower scope closer to where they are being
used.

> > 5. use_slot_in_query
> >
> > +static bool
> > +use_slot_in_query(char *slot_name, Oid *dbids)
> >
> > There are multiple non-standard for-loop variable declarations in this function.
> >
>
> fixed.

Yes, new declarations were added, but some of them (e.g. 'j') could
have been declared at a lower scope closer to where they are being
used.

> > 11. get_remote_invalidation_cause
> >
> > +/*
> > + * Get Remote Slot's invalidation cause.
> > + *
> > + * This gets invalidation cause of remote slot.
> > + */
> > +static ReplicationSlotInvalidationCause
> > +get_remote_invalidation_cause(WalReceiverConn *wrconn, char *slot_name)
> > +{
> >
> > Isn't that function comment just repeating itself?
> >
>
> Fixed.

/remote slot./the remote slot./

> > 27.
> > + /* We are done, free remot_slot_list elements */
> > + foreach(cell, remote_slot_list)
> > + {
> > + RemoteSlot *remote_slot = (RemoteSlot *) lfirst(cell);
> > +
> > + pfree(remote_slot);
> > + }
> >
> > 27a.
> > /remot_slot_list/remote_slot_list/
> >
>
> Fixed.
>
> > ~
> >
> > 27b.
> > Isn't this just the same as the one-liner:
> >
> > list_free_deep(remote_slot_list);

It looks like the #27b comment was accidentally missed (??)

> > 29. remote_connect
> >
> > +/*
> > + * Connect to remote (primary) server.
> > + *
> > + * This uses primary_conninfo in order to connect to primary. For slot-sync
> > + * to work, primary_conninfo is expected to have dbname as well.
> > + */
> > +static WalReceiverConn *
> > +remote_connect()
> >
> > 29a.
> > I felt it might be more helpful to say "GUC primary_conninfo" instead
> > of just 'primary_conninfo' the first time this is mentioned.
> >
>
> fixed.

The changed v21 comment now refers to "GUC PrimaryConnInfo" but I
think that is wrong. The GUC really is called "pnmary_conninfo" ---
PrimaryConnInfo is just the code static variable name.

======
Kind Regards,
Peter Smith.
Fujitsu Australia