Обсуждение: Queries Regarding Postgresql Replication

Поиск
Список
Период
Сортировка

Queries Regarding Postgresql Replication

От
Nithya Rajendran
Дата:

Hi ,

I have some couple of queries while doing postgres replication,

 

===> How to find whether current postgres is running as master or slave?

====> What is the procedure to make the failed master as working slave?


Could you please clarify above queries.

 

Thanks and Regards

Nithya R

Lead Engineer| Tel-Pw-LTE| AMB-5

HCL Technologies | Chennai- 600 058

cid:image001.jpg@01CA5BD7.7C7E03D0

 


::DISCLAIMER::
-----------------------------------------------------------------------------------------------------------------------

The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only.
It shall not attach any liability on the originator or HCL or its affiliates. Any views or opinions presented in
this email are solely those of the author and may not necessarily reflect the opinions of HCL or its affiliates.
Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of
this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have
received this email in error please delete it and notify the sender immediately. Before opening any mail and
attachments please check them for viruses and defect.

-----------------------------------------------------------------------------------------------------------------------
Вложения

Re: Queries Regarding Postgresql Replication

От
Josh Kupershmidt
Дата:
On Thu, May 5, 2011 at 7:33 AM, Nithya Rajendran <r-nithya@hcl.com> wrote:

[Disclaimer: I have minimal experience with hot standby, the below is
just from reading the docs]

> ===> How to find whether current postgres is running as master or slave?

SELECT pg_is_in_recovery();
will tell you (should be false for the master, true for the slave).

> ====> What is the procedure to make the failed master as working slave?

You mean, after you've failed over from A to B, how to bring A back up
as a slave of B? You should be able to just follow the steps of
setting up a master-slave pair, with B as the new master, and A the
new slave.

Josh

Re: Queries Regarding Postgresql Replication

От
senthilnathan
Дата:
*====> What is the procedure to make the failed master as working slave?*

Check whether the following steps works for you...

Assume the following is your use case.,

Master  ----> Slave(Stand by..)

Master replicating to slave. At time when master failed, the slave takes
over as new master. Now  your requirement to restart the failed master and
reconfigure the same as standby for the new master.

Stop the failed master.

1. Once the stand by taken over as master (once recovery.done and before any
new data inserted...), copy file pg_control (available under data/global/)
and the newly generated timeline history file available under archive folder
(e-g., file like 00000002.history)

2. Remove all files under pg_xlog directory and in archive folder in the
failed master . The above copied pg_control file, should be replaced in this
failed master under data/global/). The above copied history should be copied
in archive folder.

Reconfigure the recovery.conf to point the new master

Try starting the server..,(new standby) I hope it works !


- Senthil

--
View this message in context:
http://postgresql.1045698.n5.nabble.com/Queries-Regarding-Postgresql-Replication-tp4372554p4659365.html
Sent from the PostgreSQL - general mailing list archive at Nabble.com.

Re: Queries Regarding Postgresql Replication

От
senthilnathan
Дата:
*====> What is the procedure to make the failed master as working slave?*

Check whether the following steps works for you...

Assume the following is your use case.,

Master  ----> Slave(Stand by..)

Master replicating to slave. At time when master failed, the slave takes
over as new master. Now  your requirement to restart the failed master and
reconfigure the same as standby for the new master.

Stop the failed master.

1. Once the stand by taken over as master (once recovery.done and before any
new data inserted...), copy file pg_control (available under data/global/)
and the newly generated timeline history file available under archive folder
(e-g., file like 00000002.history)

2. Remove all files under pg_xlog directory and in archive folder in the
failed master . The above copied pg_control file, should be replaced in this
failed master under data/global/). The above copied history should be copied
in archive folder.

Reconfigure the recovery.conf to point the new master

Try starting the server..,(new standby) I hope it works !

Regards
Senthil

--
View this message in context:
http://postgresql.1045698.n5.nabble.com/Queries-Regarding-Postgresql-Replication-tp4372554p4659360.html
Sent from the PostgreSQL - general mailing list archive at Nabble.com.