Re: Re: BUG #13685: Archiving while idle every archive_timeout with wal_level hot_standby

On 2016-02-04 18:21:41 +0530, Amit Kapila wrote:
> I think generally it is good idea, but one thing worth a thought is that
> by doing so, we need to acquire all WAL Insertion locks every
> LOG_SNAPSHOT_INTERVAL_MS to check the last_insert_pos for
> every slot, do you think it is matter of concern in any way for write
> workloads or it won't effect as we need to do this periodically?

Michael and I just had an in-person discussion, and one of the topics
was that. The plan was basically to adapt the patch to:
1) Store the progress lsn inside the wal insert lock
2) Change the HasActivity API to return an the last LSN at which there
was activity, instead of a boolean.
2) Individually acquire each insert locks's lwlock to get it's progress
LSN, but not the exclusive insert lock. We need the lwllock to avoid
a torn 8byte read on some platforms.

I think that mostly should address your concerns?

Andres