[pgpool-general: 3203] Re: making sense of the output of "show pool_pools"

Yaron Naveh yaronn01 at gmail.com
Thu Sep 25 19:14:44 JST 2014


Hi Kent

Do you mean number of open connections from pgpool to DB or the subset of
these connections that are currently hold by active clients?

Both you can get from pool_pools. Every raw with backend_id is an existing
connection between pgpool and one of the DB nodes. If the last field
pool_connected equals 1 then this raw also represents a client which
currently holds this connection. This does not necessarily mean the DB
actually executes a query on this connection right now - this you can only
tell from SELECT * FROM pg_stat_activity.

For more information search "SHOW pool_pools" here:
http://www.pgpool.net/docs/latest/pgpool-en.html

Thanks,
Yaron

On Thu, Sep 25, 2014 at 12:59 PM, Kent Tong <kent.tong.mo at gmail.com> wrote:

> Hi Yaron,
>
> Thanks for the clear explanation! Is there any way to find the number of
> current connections from pgpool clients?
>
> On Thu, Sep 25, 2014 at 5:43 PM, Yaron Naveh <yaronn01 at gmail.com> wrote:
>
>> Hi Kent
>>
>> The documentation was updated today (as least in source) to reflect that
>> if you have multiple backends then the number of entries will
>> be num_init_children*max_pools*num_backends. You probably have 2 backends
>> which can be reflected with the backend_id field in pool_pools.
>>
>> If you have one backend then yes, a pool is a single connection that gets
>> reused. So you have exactly num_init_children child processes each
>> containing up to max_pool pools (=connections), each one to a different
>> db/user combination. If you have multiple backends then each pool will
>> contain one connection per backend (for the same db/user combination).
>>
>> Thanks,
>> Yaron
>>
>> On Thu, Sep 25, 2014 at 12:18 PM, Kent Tong <kent.tong.mo at gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> How to interpret the output of "show pool_pools"? What is a "pool"
>>> anyway? Is it a single connection that gets reused? My num_init_children is
>>> 50 and max_pool lines is 4, the doc says that it will list 200 entries but
>>> 400 were listed. Why? In particular, I found entries with identical
>>> pool_pid+pool_id.
>>>
>>> Thanks in advance!
>>>
>>> --
>>> Kent Tong
>>> IT author and consultant, child education coach
>>>
>>> _______________________________________________
>>> pgpool-general mailing list
>>> pgpool-general at pgpool.net
>>> http://www.pgpool.net/mailman/listinfo/pgpool-general
>>>
>>>
>>
>>
>> --
>>
>> I'm on Twitter (@YaronNaveh <http://twitter.com/#!/YaronNaveh>)
>>
>
>
>
> --
> Kent Tong
> IT author and consultant, child education coach
>
> _______________________________________________
> pgpool-general mailing list
> pgpool-general at pgpool.net
> http://www.pgpool.net/mailman/listinfo/pgpool-general
>
>


-- 

I'm on Twitter (@YaronNaveh <http://twitter.com/#!/YaronNaveh>)
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