Re: Synchronizing slots from primary to standby

On Mon, Nov 20, 2023 at 4:28 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> 9.
> +synchronize_one_slot(WalReceiverConn *wrconn, RemoteSlot *remote_slot,
> + bool *slot_updated)
> {
> ...
> + else
> + {
> + TransactionId xmin_horizon = InvalidTransactionId;
> + ReplicationSlot *slot;
> +
> + ReplicationSlotCreate(remote_slot->name, true, RS_EPHEMERAL,
> +   remote_slot->two_phase, false);
> + slot = MyReplicationSlot;
> +
> + SpinLockAcquire(&slot->mutex);
> + slot->data.database = get_database_oid(remote_slot->database, false);
> +
> + /* Mark it as sync initiated by slot-sync worker */
> + slot->data.sync_state = SYNCSLOT_STATE_INITIATED;
> + slot->data.failover = true;
> +
> + namestrcpy(&slot->data.plugin, remote_slot->plugin);
> + SpinLockRelease(&slot->mutex);
> +
> + ReplicationSlotReserveWal();
> +
>
> How and when will this init state (SYNCSLOT_STATE_INITIATED) persist to disk?
>

On closer inspection, I see that it is done inside
wait_for_primary_and_sync() when it fails to sync. I think it is
better to refactor the code a bit and persist it in
synchronize_one_slot() to make the code flow easier to understand.

--
With Regards,
Amit Kapila.