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

[鈴木 幸市 <ko...@in...>]

No, ALTER TABLE tablename DELETE NODE (nodename);

This is very similar to the thing you should do to add the node

ALTER TABLE table name ADD NODE (ndoename);

It is included in my demo story at the last PG Open presentation.

If you’re not sure, you can test it using smaller work table.

Regards;
---
Koichi Suzuki

2014/04/18 16:54、Juned Khan <jkh...@gm...> のメール：

> 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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>>> 
>> 
>> 
>> 
>> --
>