Re: [Postgres-xc-general] Infrastructure Suggestions

You should be careful about max_connections and
max_prepared_transactions.    They should at least be (max_connections
at coordinator) * (number of coordinators) respectively.

Regards;
----------
Koichi Suzuki


2013/1/16 Ashutosh Bapat <ash...@en...>:
> For datanodes, you can configure it much like PostgreSQL. But
> coordinators are a bit tricky.
>
> If you have distributed your tables such that most of your queries are
> being run on datanode, you can do with medium sized work mem. You
> don't need much buffer space, except for catalog queries. Now, how do
> we detect, how much of the query is being run on the datanode? In the
> explain outputs of plans steps with labels "Data node scan" are
> executed on datanodes, whereas any other steps are run at coordinator.
> If you see a lot of steps being executed on the coordinator, you need
> more memory and CPU resources at the coordinator.
>
> On Wed, Jan 16, 2013 at 4:49 AM, Michael Paquier
> <mic...@gm...> wrote:
>>
>>
>> On Wed, Jan 16, 2013 at 12:41 AM, Arni Sumarlidason
>> <Arn...@md...> wrote:
>>>
>>> Good Morning Everyone,
>>>
>>>
>>>
>>> We are setting up a 25 node postgres-xc cluster, does anyone have suggests
>>> on how much disk space a coordinator uses with its local database?
>>
>> Not that much, Coordinator contains only catalog information. I let at your
>> appreciation the amount of space you think you need, but not gigs for sure.
>>
>>> Also hints regarding the memory section in postgresql.conf would be
>>> awesome!
>>
>> I would do the settings of shared_buffers, work_mem, maintenance_work_mem
>> and effective cache size on Datanodes as on normal PostgreSQL servers.
>> For Coordinators, you don't need that much memory except if you have sort
>> operations happening there, in this case adapt work_mem. You can also set up
>> shared_buffers to put all the catalog information on-cache, but I do not
>> think it is that much a win.
>>
>> Thanks,
>> --
>> Michael Paquier
>> http://michael.otacoo.com
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>
>
>
> --
> Best Wishes,
> Ashutosh Bapat
> EntepriseDB Corporation
> The Enterprise Postgres Company
>
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