RE: Synchronizing slots from primary to standby

On Monday, January 22, 2024 11:36 AM shveta malik <shveta.malik@gmail.com> wrote:

Hi,

> On Fri, Jan 19, 2024 at 4:18 PM shveta malik <shveta.malik@gmail.com> wrote:
> >
> > PFA v64.
> 
> V64 fails to apply to HEAD due to a recent commit. Rebased it. PFA v64_2. It has
> no new changes.

I noticed few things while analyzing the patch.

1.
sleep_ms = Min(sleep_ms * 2, MAX_WORKER_NAPTIME_MS);

The initial value for sleep_ms is 0(default value for static variable) which
will not be advanced in this expression. We should initialize sleep_ms to a positive
number.

2.
        / Wait a bit, we don't expect to have to wait long /
        rc = WaitLatch(MyLatch,
                       WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
                       10L, WAIT_EVENT_BGWORKER_SHUTDOWN);

The slotsync worker is not a bgworker anymore after 0003 patch, so a new event
is needed I think.

3.
slot->effective_catalog_xmin = xmin_horizon;

The assignment is also needed in local_slot_update() to make 
ReplicationSlotsComputeRequiredXmin work.

Best Regards,
Hou zj