Re: Syncrep and improving latency due to WAL throttling

Hi,

On 2023-01-26 13:33:27 +0530, Bharath Rupireddy wrote:
> 6. Backends can ignore throttling for WAL records marked as unimportant, no?

Why would that be a good idea? Not that it matters today, but those records
still need to be flushed in case of a commit by another transaction.


> 7. I think we need to not let backends throttle too frequently even
> though they have crossed wal_throttle_threshold bytes. The best way is
> to rely on replication lag, after all the goal of this feature is to
> keep replication lag under check - say, throttle only when
> wal_distance > wal_throttle_threshold && replication_lag >
> wal_throttle_replication_lag_threshold.

I think my idea of only forcing to flush/wait an LSN some distance in the past
would automatically achieve that?

Greetings,

Andres Freund