Re: [Postgres-xc-general] Problem with starting datanode slave

[Juned K. <jkh...@gm...>]

You mean first i have to modify my table structure lets consider i
have replicated tables so  i have to remove "DISTRIBUTE by
REPLICATION" right ?

And then i have to run DROP node command to remove datanode slave

pgxc_ctl won't do it for me ?
i.e
PGXC remove datanode slave datanode1

PGXC add datanode slave datanode3 node5 20008 /home/postgres/pgxc/nodes/dn_slave

And how it will copy database after adding datanode slave ?



On Fri, Apr 18, 2014 at 12:59 PM, 鈴木 幸市 <ko...@in...> wrote:
> Reverse order.
>
> First, exclude removing node from the node set your tables are distributed
> or replicated.    You can do this with ALTER TABLE.   All the row in the
> table will be redistributed to modified set of nodes for distributed tables.
> In the case of replicated tables, tables in the removing node will just be
> detached.
>
> Then, you can issue DROP NODE before you really stop and clear the node
> resource.
> ---
> Koichi Suzuki
>
> 2014/04/18 16:13、Juned Khan <jkh...@gm...> のメール：
>
> what if i just remove datanode slave and add it again ? all data will be
> copied to slave ?
> will it impact on master ?
>
>
> On Fri, Apr 18, 2014 at 6:29 AM, 鈴木 幸市 <ko...@in...> wrote:
>>
>> The impact to the master server is almost the same as in the case of
>> vanilla PG to build a slave using pg_basebackup.   It sends all the master
>> database file resource to the slave together with its WAL.   Good thing
>> compared with more primitive way of pg_start_backup() and pg_stop_backup()
>> is the data are read directly from the cache so impact to I/O workload will
>> be smaller.
>>
>> If you’re concerning safety to the master resource, there could be another
>> means, for example, to stop the master, copy everything to the slave, change
>> master to enable WAL shipping and slave to run as the slave.   Principally,
>> this should work and you can keep the master resource safer but I’ve not
>> tested this yet.
>>
>> Regards;
>> ---
>> Koichi Suzuki
>>
>> 2014/04/17 20:23、Juned Khan <jkh...@gm...> のメール：
>>
>> Hi koichi,
>>
>> Is there any other short solution to fix this issue ?
>>
>> 1. Run checkpoint and vacuum full at the master,
>>     Found the docs to perform vacuum full but i have confusion about how
>> to run checkpoint manually.
>>
>> 2. Build the slave from the scotch using pg_basebackup (pgxc_ctl provides
>> this means).
>>     should i run this command from datanode slave server something like (
>> pg_basebackup -U postgres -R -D /srv/pgsql/standby --host=192.168.1.17
>> --port=5432)
>>
>> And very important thing how it will impact on datanode master server ? as
>> of now i have only this master running on server.
>> so as of now i just don't want to take a chance, and somehow want to start
>> slave for backup.
>>
>> Please advice
>>
>> Regards
>> Juned Khan
>>
>> On Thu, Apr 17, 2014 at 4:43 PM, Juned Khan <jkh...@gm...> wrote:
>>>
>>> so i have to do experiment for this. i really need that much connection.
>>>
>>> Thanks for  the suggestion  @Michael
>>>
>>>
>>> On Thu, Apr 17, 2014 at 11:40 AM, Michael Paquier
>>> <mic...@gm...> wrote:
>>>>
>>>> On Thu, Apr 17, 2014 at 2:51 PM, Juned Khan <jkh...@gm...> wrote:
>>>> > And i can use pgpool and pgbouncer with pgxc right ?
>>>> In front of the Coordinators, that's fine. But I am not sure in from
>>>> of the Datanodes as XC has one extra connection parameter to identify
>>>> the node type from which connection is from, and a couple of
>>>> additional message types to pass down transaction ID, timestamp and
>>>> snapshot data from Coordinator to Datanodes (actually Coordinators as
>>>> well for DDL queries). If those message types and/or connection
>>>> parameters get filtered by pgpool or pgbouncer, well you cannot use
>>>> them. I've personally never given a try though, but the idea is worth
>>>> an attempt to reduce lock contention that could be caused by a too
>>>> high value of max_connections.
>>>> --
>>>> Michael
>>>
>>>
>>>
>>>
>>
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