Re: logical replication worker and statistics

> On 10 Apr 2017, at 05:20, Noah Misch <noah(at)leadboat(dot)com> wrote:
>
> On Wed, Apr 05, 2017 at 05:02:18PM +0300, Stas Kelvich wrote:
>>> On 27 Mar 2017, at 18:59, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> On Mon, Mar 27, 2017 at 11:14 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>>>> Logical replication worker should call pgstat_report_stat()?
>>>> Currently it doesn't seem to do that and no statistics about
>>>> table accesses by logical replication workers are collected.
>>>> For example, this can prevent autovacuum from working on
>>>> those tables properly.
>>>
>>> Yeah, that doesn't sound good.
>>
>> Seems that nobody is working on this, so i’m going to create the patch.
>
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>
> The above-described topic is currently a PostgreSQL 10 open item. Peter,
> since you committed the patch believed to have created it, you own this open
> item. If some other commit is more relevant or if this does not belong as a
> v10 open item, please let us know. Otherwise, please observe the policy on
> open item ownership[1] and send a status update within three calendar days of
> this message. Include a date for your subsequent status update. Testers may
> discover new open items at any time, and I want to plan to get them all fixed
> well in advance of shipping v10. Consequently, I will appreciate your efforts
> toward speedy resolution. Thanks.
>
> [1] https://www.postgresql.org/message-id/20170404140717.GA2675809%40tornado.leadboat.com

Here is small patch to call statistics in logical worker. Originally i thought that stat
collection during logical replication should manually account amounts of changed tuples,
but seems that it is already smoothly handled on relation level. So call to
pgstat_report_stat() is enough.

Also i’ve added statistics checks to logrep tap tests, but that is probably quite fragile
without something like wait_for_stats() from regression test stats.sql.