[pgpool-hackers: 679] Re: Logging load balancing result

[Tatsuo Ishii]

> Hi
> 
> I think this is a very good idea, and a much needed feature. As load
> balancing is one of the prime feature of the pgpool-II and getting
> these stats will be very helpful and informative.
> 
> Although I think having the ability to reset stats should also be
> included as the part of this feature and it would be nice to add a
> pool_ command to check the stats reset time.

Good idea. I think we would need new pcp command to reset stats.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> Kind regards,
> Muhammad Usama
> 
> On Fri, Nov 21, 2014 at 5:07 AM, Tatsuo Ishii <ishii at postgresql.org> wrote:
>> Hi,
>>
>> We are frequently asked a way to know how SELECTs are load balanced
>> among database nodes. For now there are two ways:
>>
>> 1) enable log_per_node_statement and grep pgpool.log
>>
>> 2) enable log_statement and grep PostgreSQL log
>>
>> Both increase log volume and are needed to create scripts or set up
>> external monitoring tools such as zabbix. Also I feel #1 and #2 are
>> overkill for those who just want to know number of SELECTs load
>> balanced and are not interested in individual SELECT statement.
>>
>> So I would like to propose to add new functionality to allow to gather
>> load balancing statistics. The result will be shown using "show
>> pool_nodes" command in a new column "lbs_stat".
>>
>> => show pool_nodes;
>>  node_id | hostname | port  | status | lb_weight |  role   | lbs_stat
>> ---------+----------+-------+--------+-----------+---------+---------
>>  0       | /tmp     | 11000 | 2      | 0.333333  | primary | 12345
>>  1       | /tmp     | 11001 | 2      | 0.333333  | standby | 45678
>>  2       | /tmp     | 11002 | 2      | 0.333333  | standby | 56789
>>
>> Here lbs_stat indicates how many SELECTs are load balanced to each node.
>>
>> The load balancing statistics are accumulated in a shared memory area
>> and will have quite little overhead. So I feel there's no need to the
>> functionality turned off.
>>
>> Comments and suggestions are welcome.
>>
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
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