Re: [Postgres-xc-developers] Steps to remove coordinator master

[Amit K. <ami...@en...>]

On 13 May 2013 11:52, Abbas Butt <abb...@en...> wrote:

>
>
> On Mon, May 13, 2013 at 10:52 AM, Ashutosh Bapat <
> ash...@en...> wrote:
>
>> Hi Abbas,
>> Why is DROP NODE executing EXEC DIRECT ON? The internal code shouldn't do
>> this. EXEC DIRECT is only for debug purposes and can be deprecated in
>> future. In fact, I am leaning to remove it. It's complicating matters a lot.
>>
>
> DROP NODE does not issue EXECUTE DIRECT, it tries to acquire an advisory
> lock and our implementation of advisory lock uses EXEC DIRECT. Please take
> a look at the function pgxc_advisory_lock. Amit can explain it more.
>

In order to send pg_advisory_lock() in serial manner, one each of the node
one after the other, I had to do this. I guess Michael has now written some
helper functions to execute commands on particular node, which we can use
instead of exec_direct.


>
>
>>
>>
>> On Mon, May 13, 2013 at 11:03 AM, Abbas Butt <abb...@en...
>> > wrote:
>>
>>>
>>>
>>> On Mon, May 13, 2013 at 9:31 AM, Koichi Suzuki <
>>> koi...@gm...> wrote:
>>>
>>>> Hello;
>>>>
>>>> I'm testing pgxc_ctl to remove a coordinator master.   Following your
>>>> suggestions, I first stopped the coordinator master to be removed and then
>>>> issued "drop node" in all the other coordinators.   Somehow drop node
>>>> complains that it fails to obtain pooled connection, in fact, in drop node,
>>>> "execute direct on (node_to_be_removed)" was issued.
>>>>
>>>> It worked fine if the removed coordinator is stopped after all the DROP
>>>> NODE are successful.
>>>>
>>>> Did you issue CLEAN CONNECTION or pgxc_pool_reload before you issue
>>>> "DROP NODE"?
>>>>
>>>
>>> No, I did not issue any such statement. I just tested again and I am
>>> also getting the following error when I issue DROP NODE
>>> test=# drop node coord_2;
>>> ERROR:  Failed to get pooled connections
>>> CONTEXT:  SQL statement "EXECUTE DIRECT ON (coord_2) 'SELECT
>>> pg_catalog.pg_try_advisory_xact_lock_shared(65535, 0)'"
>>> test=#
>>>
>>> This is a bug and has to be fixed. The bug is that DROP NODE should not
>>> be trying to acquire the lock. I will send a fix for this today. The steps
>>> remain the same as before.
>>>
>>>
>>>
>>>>
>>>> Regards;
>>>> ----------
>>>> Koichi Suzuki
>>>>
>>>
>>>
>>>
>>> --
>>> --
>>> *Abbas*
>>>  Architect
>>>
>>> Ph: 92.334.5100153
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>>
>>
>> --
>> Best Wishes,
>> Ashutosh Bapat
>> EntepriseDB Corporation
>> The Postgres Database Company
>>
>
>
>
> --
> --
> *Abbas*
>  Architect
>
> Ph: 92.334.5100153
>  Skype ID: gabbasb
> www.enterprisedb.co <http://www.enterprisedb.com/>m<http://www.enterprisedb.com/>
> *
> Follow us on Twitter*
> @EnterpriseDB
>
> Visit EnterpriseDB for tutorials, webinars, whitepapers<http://www.enterprisedb.com/resources-community>and more<http://www.enterprisedb.com/resources-community>
>
>
> ------------------------------------------------------------------------------
> Learn Graph Databases - Download FREE O'Reilly Book
> "Graph Databases" is the definitive new guide to graph databases and
> their applications. This 200-page book is written by three acclaimed
> leaders in the field. The early access version is available now.
> Download your free book today! http://p.sf.net/sfu/neotech_d2d_may
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