Re: Fix of doc for synchronous_standby_names.

From: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
To: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, robertmhaas(at)gmail(dot)com
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Fix of doc for synchronous_standby_names.
Date: 2016-04-21 05:01:41
Message-ID: 57185EB5.5090708@lab.ntt.co.jp
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On 2016/04/21 12:25, Kyotaro HORIGUCHI wrote:
> At Wed, 20 Apr 2016 23:07:41 -0400, Robert Haas wrote:
>> On Sun, Apr 17, 2016 at 11:56 PM, Kyotaro HORIGUCHI wrote:
>>>
>>>> There is no mechanism to enforce uniqueness. In case of
>>>> duplicates one of the matching standbys will be considered as
>>>> higher priority, though exactly which one is indeterminate.
>>>
>>> The patch attatched edits the above to the following.
>>>
>>>> There is no mechanism to enforce uniqueness. In case of
>>>> duplicates some of the matching standbys will be considered as
>>>> higher priority, though they are chosen in an indeterminate way.
>>>
>>> Is this makes sense?
>>
>> I don't see what the problem is with the existing language. I don't
>> find your rewrite to be clearer.
>
> My first sentense shows my concern. I don't want make something
> clear but want to fix the description that seems to me to be
> wrong.
>
> If the exising description fits the case that two or more
> matching standbys are choosed as 'higher priority', I'm quite bad
> in reading..

ISTM, the sentence describes what happens in a *single instance* of
encountering duplicate (same name found in primary_conninfo of 2 or more
standbys). It's still one name but which of the standbys claims the spot
(for that name) of being a synchronous standby with given priority is
indeterminate.

Now, there can be multiple instances of encountering duplicates, each for
a different sync slot. But this particular sentence seems to be talking
about what's the case for any given slot.

Does that make sense?

Thanks,
Amit

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