Re: Blocked updates and background writer performance

On Wed, Jan 13, 2016 at 11:51 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> Anyway, it looks to me like you have a checkpoint problem. The checkpoint
> overwhelms your IO system. The overwhelmed IO system then backs up into
> the bgwriter. What you see in the bgwriter is just a symptom, not the
> cause. The background writer is usually not very useful in recent versions
> of PostgreSQL, anyway. But, the same IO problem that is clogging up the
> background writer is also clogging up either your buffer_backend, or your
> WAL writes/fsyncs. And both of those will destroy your throughput.
>

That was my intuition too. Not enough I/O available from the hardware for
the workload requested.

As recommended, log your checkpoints and try tuning them to spread the load.