Re: Logical Decoding Failover

Venkata,

Thanks for the reply. Unfortunately something like PgPool still won't
create the replication slots on all hosts, and record the LSN in a way that
is reusable on the secondary.

This sort of puts logical decoding at odds with HA, correct? In the case of
master failover, there's no way to: a) know where in the stream you read
to, or b) convert that to something that can be understood by a replica
that's about to be promoted.

Are there any scheduled improvements here either for 9.6 or 9.7?

Best,
Colin
On Sun, Aug 7, 2016 at 1:50 AM Venkata Balaji N <nag1010(at)gmail(dot)com> wrote:

> On Sat, Aug 6, 2016 at 1:17 PM, Colin Morelli <colin(dot)morelli(at)gmail(dot)com>
> wrote:
>
>> Hey all,
>>
>> I'm using logical decoding in my application to capture change streams
>> and ship them to Kafka. However, logical replication slots aren't included
>> in the WAL and thus don't make it to replicas. In the case of a failover,
>> it's not clear what (if anything) can be done to continue receiving a
>> change stream.
>>
>> I noticed there was a failover slot patch that looks like it won't be
>> making it for 9.6 (if at all), but does anyone else have suggestions for
>> handling failover + logical decoding? Is there an answer, or is it limited
>> to being a very manual process for now?
>>
>
> Yes, as of i know, It is a manual process for now. Another alternative you
> can consider (if possible at all) would be a tool like PgPool-II which is
> actually used for connection pooling, load balancing and automatic
> failover. It may not make sense if you are do not wish to pool you
> connections.
>
> Regards,
> Venkata B N
>
> Fujitsu Australia
>