[pgpool-hackers: 1646] Re: kind does not match error in pgpool

[Tatsuo Ishii]

> Hi Ishii-San
> 
> Can you please have a look at the attached patch, It try to solve this
> "Kind does not match .." problem by ignoring the notice messages while
> reading the backend response in read_kind_from_backend() function

Doesn't this patch simply ignore important messages like this?

>>> ... WARNING: database "testdb" must be vacuum within 11000000 transaction

> 
> 
> On Tue, Apr 19, 2016 at 1:50 PM, Ahsan Hadi <ahsan.hadi at enterprisedb.com>
> wrote:
> 
>> I agree this cause lot of annoyance to pgpool users and something we
>> should address for 3.6.
>>
>> Usama,
>> Is this added to 3.6 wiki?
>>
>> On Fri, Apr 15, 2016 at 11:46 AM, Muhammad Usama <m.usama at gmail.com>
>> wrote:
>>
>>> Hi
>>>
>>> pgpool throws ".. kind does not match.." error message when all the
>>> attached backend nodes do not return the same response to the query. Although
>>> this error message can be a symptom of the backend node sync issue in
>>> most cases, but in case when the message kind of backend nodes differs
>>> because one of the backend returned the notice response while the other
>>> returned some other kind then that case should not be considered as an
>>> error case.
>>>
>>> Consider the scenario where a pgpool is connected to three backend nodes
>>> and pgpool is expecting to receive "[C] command complete" message from
>>> all nodes for the last query. But while processing the query one of the
>>> backend also produced a warning message.
>>>
>>> ... WARNING: database "testdb" must be vacuum within 11000000 transaction
>>>
>>> Please note that the query was successful on all attached backend, but
>>> one backend also produced an extra warning message along with the command
>>> complete message.
>>>
>>> Now pgpool will throw an error something like
>>>
>>> ERROR: pid 720: read_kind_from_backend: 1 th kind N does not match
>>> with master or majority connection kind C
>>>
>>> But since the node would also have sent the expected command complete
>>> message after that warning notice, So Ideally, pgpool should ignore the
>>> WARNING message and compare the subsequent message, and only throw an error
>>> if the message from nodes after ignoring notification messages differs.
>>>
>>> What are your thoughts on this?
>>>
>>> Kind regards
>>> Muhammad Usama
>>>
>>>
>>> _______________________________________________
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>>>
>>>
>>
>>
>> --
>> Ahsan Hadi
>> Snr Director Product Development
>> EnterpriseDB Corporation
>> The Enterprise Postgres Company
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