Re: stats for network traffic WIP

On Wed, Nov 20, 2013 at 3:18 AM, Atri Sharma <atri(dot)jiit(at)gmail(dot)com> wrote:
> On Tue, Nov 19, 2013 at 11:43 PM, Mike Blackwell <mike(dot)blackwell(at)rrd(dot)com> wrote:
>> This patch looks good to me. It applies, builds, and runs the regression
>> tests. Documentation is included and it seems to do what it says. I don't
>> consider myself a code expert, but as far as I can see it looks fine. This
>> is a pretty straightforward enhancement to the existing pg_stat_* code.
>>
>> If no one has any objections, I'll mark it ready for committer.
>>
>> Mike
>
> I agree.
>
> I had a discussion with Mike yesterday, and took the performance areas
> in the patch. I think the impact would be pretty low and since the
> global counter being incremented is incremented with keeping race
> conditions in mind, I think that the statistics collected will be
> valid.
>
> So, I have no objections to the patch being marked as ready for committer.

Could you share the performance numbers? I'm really concerned about
the performance overhead caused by this patch.

Here are the comments from me:

All the restrictions of this feature should be documented. For example,
this feature doesn't track the bytes of the data transferred by FDW.
It's worth documenting that kind of information.

ISTM that this feature doesn't support SSL case. Why not?

The amount of data transferred by walreceiver also should be tracked,
I think.

I just wonder how conn_received, conn_backend and conn_walsender
are useful.

Regards,

--
Fujii Masao