Thread: write on standby

write on standby

From
Julie Nishimura
Date:
Hello there,
Is it possible for a test app to connect to the standby dB of an active-Standby dB pair?  While both continue to be connected and replicating? What if it’s needed to write tmp tables that are later dropped? Can it be done in hot standby scenario on standby? Version is 9.6.2

Thanks

Re: write on standby

From
Adrian Klaver
Date:
On 3/5/19 3:34 PM, Julie Nishimura wrote:
> Hello there,
> Is it possible for a test app to connect to the standby dB of an 
> active-Standby dB pair?  While both continue to be connected and 
> replicating? What if it’s needed to write tmp tables that are later 
> dropped? Can it be done in hot standby scenario on standby? Version is 9.6.2

No:

https://www.postgresql.org/docs/9.6/hot-standby.html

26.5.1. User's Overview

In particular:

"Data Definition Language (DDL) - CREATE, DROP, ALTER, COMMENT. This 
restriction applies even to temporary tables, because carrying out these 
operations would require updating the system catalog tables."

> 
> Thanks


-- 
Adrian Klaver
adrian.klaver@aklaver.com


Re: write on standby

From
Andreas Kretschmer
Date:

Am 06.03.19 um 00:34 schrieb Julie Nishimura:
> Hello there,
> Is it possible for a test app to connect to the standby dB of an 
> active-Standby dB pair?

that's possible, but ...


> While both continue to be connected and replicating? What if it’s 
> needed to write tmp tables that are later dropped?

... that's not. Not with streaming replication, but ...


> Can it be done in hot standby scenario on standby? Version is 9.6.2
>

... it would be possible with logical replication (trigger based 
solutions like slony or lindiste or logical replication using pglogical 
from us, 2ndQ).

https://www.2ndquadrant.com/en/resources/pglogical/


You can also use BDR2 with PG9.6, but this is only available for our 
customers.


Regards, Andreas

-- 
2ndQuadrant - The PostgreSQL Support Company.
www.2ndQuadrant.com



Re: write on standby

From
Julie Nishimura
Date:
Thank you. Are you going to have any presentations on Postgresql conference in NYC soon?


From: Andreas Kretschmer <andreas@a-kretschmer.de>
Sent: Tuesday, March 5, 2019 9:16 PM
To: pgsql-general@lists.postgresql.org
Subject: Re: write on standby
 


Am 06.03.19 um 00:34 schrieb Julie Nishimura:
> Hello there,
> Is it possible for a test app to connect to the standby dB of an
> active-Standby dB pair?

that's possible, but ...


> While both continue to be connected and replicating? What if it’s
> needed to write tmp tables that are later dropped?

... that's not. Not with streaming replication, but ...


> Can it be done in hot standby scenario on standby? Version is 9.6.2
>

... it would be possible with logical replication (trigger based
solutions like slony or lindiste or logical replication using pglogical
from us, 2ndQ).

https://www.2ndquadrant.com/en/resources/pglogical/


You can also use BDR2 with PG9.6, but this is only available for our
customers.


Regards, Andreas

--
2ndQuadrant - The PostgreSQL Support Company.
www.2ndQuadrant.com


Re: write on standby

From
Andreas Kretschmer
Date:
On 6 March 2019 06:26:45 CET, Julie Nishimura <juliezain@hotmail.com> wrote:
>Thank you. Are you going to have any presentations on Postgresql
>conference in NYC soon?
>
>________________________________
>From: Andreas Kretschmer <andreas@a-kretschmer.de>
>Sent: Tuesday, March 5, 2019 9:16 PM
>To: pgsql-general@lists.postgresql.org
>Subject: Re: write on standby
>
>
>
>Am 06.03.19 um 00:34 schrieb Julie Nishimura:
>> Hello there,
>> Is it possible for a test app to connect to the standby dB of an
>> active-Standby dB pair?
>
>that's possible, but ...
>
>
>> While both continue to be connected and replicating? What if it’s
>> needed to write tmp tables that are later dropped?
>
>... that's not. Not with streaming replication, but ...
>
>
>> Can it be done in hot standby scenario on standby? Version is 9.6.2
>>
>
>... it would be possible with logical replication (trigger based
>solutions like slony or lindiste or logical replication using pglogical
>from us, 2ndQ).
>
>https://www.2ndquadrant.com/en/resources/pglogical/
>
>
>You can also use BDR2 with PG9.6, but this is only available for our
>customers.
>
>
>Regards, Andreas
>
>--
>2ndQuadrant - The PostgreSQL Support Company.
>www.2ndQuadrant.com<http://www.2ndQuadrant.com>

Hi,

I think so, if you want i can organize a contact with someone from our company.


Andreas (from germany)
--
2ndQuadrant - The PostgreSQL Support Company


Re: write on standby

From
Adrian Klaver
Date:
On 3/5/19 9:16 PM, Andreas Kretschmer wrote:
> 
> 
> Am 06.03.19 um 00:34 schrieb Julie Nishimura:
>> Hello there,
>> Is it possible for a test app to connect to the standby dB of an 
>> active-Standby dB pair?
> 
> that's possible, but ...
> 
> 
>> While both continue to be connected and replicating? What if it’s 
>> needed to write tmp tables that are later dropped?
> 
> ... that's not. Not with streaming replication, but ...
> 
> 
>> Can it be done in hot standby scenario on standby? Version is 9.6.2
>>
> 
> ... it would be possible with logical replication (trigger based 
> solutions like slony or lindiste or logical replication using pglogical 
> from us, 2ndQ).
> 
> https://www.2ndquadrant.com/en/resources/pglogical/
> 
> 
> You can also use BDR2 with PG9.6, but this is only available for our 
> customers.

Out of curiosity how did:

https://www.postgresql.org/message-id/20150831193033.GL2912%40alvherre.pgsql

https://www.postgresql.org/message-id/CAH+GA0qO0q9NJhKxaoo8CV-QR9Cuw6LtDGDb33pq16rU88F_dA@mail.gmail.com

get to?:

https://www.2ndquadrant.com/en/resources/postgres-bdr-2ndquadrant/

> 
> 
> Regards, Andreas
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com