Re: pgpool-II (max_pool and num_init_children)

Guillaume Lelarge wrote:
> Le 02/07/2010 15:46, Geoffrey a écrit :
>> Tatsuo Ishii wrote:
>>>> I'm trying to get a handle on sane values for these two parameters.
>>>> I assume that they should somehow correlate  to my existing
>>>> max_connections in my postgresql.conf file.  Anyone using pgpool-II
>>>> care to comment?
>>>>
>>>> I'm sure it's a balancing act between how many connections you want
>>>> verses how many cached connections you have, but not sure how to
>>>> properly assess this issue.
>>>>
>>>> (I've tried posting to the pgpool list, but it's apparently
>>>> unavailable at this time)
>>> Here is an recommended rule:
>>>
>>> max_pool*num_init_children <= (max_connections -
>>> superuser_reserved_connections)
>>>
>>> Because num_init_children defines the max concurrent connections
>>> pgpool-II can accept, you might want to keep num_init_children as
>>> large as possible. In this case you could lower max_pool to as low as
>>> 1, which may cause performance degration because of low effect of
>>> connection cache if you would have more than 1 user/database
>>> combinations. However lower max_pool will not any error or any
>>> problems except performance.
>> We have a complicated set up.  We have 13 databases with 12 postmasters.
>>   So that means 2 databases share a postmaster, the rest have their
>> own.  Consequently, separate pools for each postmaster.  We will
>> frequently have 20-30 or more users connecting to any one database,
>> although some databases are much lower.  This is further complicated by
>> a web application that also connects to the databases.
>>
>
> You won't be able to handle more than one postmaster with one pgPool-II
> in pooling mode. You'll need at least one pgPool-II for each postmaster.
> And so, do one configuration for each pgPool-II.

Yes, that is the intent.  But, we are considering having multiple
pgPool-II for one postmaster.

--
Until later, Geoffrey

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