Re: Adding in docs the meaning of pg_stat_replication.sync_state

On Fri, Nov 11, 2016 at 10:03 PM, Michael Paquier
<michael(dot)paquier(at)gmail(dot)com> wrote:
> On Thu, Nov 10, 2016 at 10:35 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>> On Wed, Nov 9, 2016 at 2:33 PM, Michael Paquier
>> <michael(dot)paquier(at)gmail(dot)com> wrote:
>>> Hi all,
>>>
>>> The documentation does not explain at all what means "sync" or "async"
>>> on pg_stat_replication.
>>
>> "potential" state also should be explained?
>
> Of course.
>
>>> The paragraph "Planning for high availability"
>>> mentions "catchup" and "streaming", but it does not say that users can
>>> refer to it directly in pg_stat_replication.
>>>
>>> Thoughts about the patch attached to add a couple of sentences in
>>> "Planning for high availability"? We could as well mention it directly
>>> in the page of pg_stat_replication but this information seems more
>>> suited if located in the HA section.
>>
>> Yeah, I think it's better to mention them even in pg_stat_replication page.
>
> OK, so I have done things this way. What do you think? At the same
> time it would be good to mention all the possible field values in
> "state", aka streaming, catchup, etc so I added that as well.

Thanks for the patch!

+ <literal>backup</>: The WAL sender is sending a backup.

Seems it's better to use "This WAL sender" rather than "The WAL sender"
like the descriptions of other fields.

There are two descriptions of "streaming" value. You need to remove
either of them.

+ <literal>streaming</>: The WAL sender is catching up with the
+ primary.

"walsender is catching up with the primary" sounds a bit strange to me.
What about "This WAL sender's connected standby server is catching up
with the primary"?

+ <literal>streaming</>: The WAL sender has caught up with the
+ primary and is streaming changes.

Same as above.

Regards,

--
Fujii Masao