Re: Introduce XID age and inactive timeout based replication slot invalidation

On Thu, Mar 14, 2024 at 7:58 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> While we wait to hear from others on this, I'm attaching the v9 patch
> set implementing the above idea (check 0001 patch). Please have a
> look. I'll come back to the other review comments soon.
>

patch002:

1)
I would like to understand the purpose of 'inactive_count'? Is it only
for users for monitoring purposes? We are not using it anywhere
internally.

I shutdown the instance 5 times and found that 'inactive_count' became
5 for all the slots created on that instance. Is this intentional? I
mean we can not really use them if the instance is down. I felt it
should increment the inactive_count only if during the span of
instance, they were actually inactive i.e. no streaming or replication
happening through them.

2)
slot.c:
+ case RS_INVAL_XID_AGE:
+ {
+ if (TransactionIdIsNormal(s->data.xmin))
+ {
+ ..........
+ }
+ if (TransactionIdIsNormal(s->data.catalog_xmin))
+ {
+ ..........
+ }
+ }

Can we optimize this code? It has duplicate code for processing
s->data.catalog_xmin and s->data.xmin. Can we create a sub-function
for this purpose and call it twice here?

thanks
Shveta