Re: Binary support for pgoutput plugin

On Wed, Jun 12, 2019 at 10:35:48AM -0400, Dave Cramer wrote:
>On Mon, 10 Jun 2019 at 07:49, Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>
>wrote:
>
>> Hi,
>>
>> On 10/06/2019 13:27, Dave Cramer wrote:
>> > So back to binary output.
>> >
>> > From what I can tell the place to specify binary options would be in the
>> > create publication and or in replication slots?
>> >
>> > The challenge as I see it is that the subscriber would have to be able
>> > to decode binary output.
>> >
>> > Any thoughts on how to handle this? At the moment I'm assuming that this
>> > would only work for subscribers that knew how to handle binary.
>> >
>>
>> Given that we don't need to write anything extra to WAL on upstream to
>> support binary output, why not just have the request for binary data as
>> an option for the pgoutput and have it chosen dynamically? Then it's the
>> subscriber who asks for binary output via option(s) to START_REPLICATION.
>>
>
>If I understand this correctly this would add something to the CREATE/ALTER
>SUBSCRIPTION commands in the WITH clause.
>Additionally another column would be required for pg_subscription for the
>binary option.
>Does it make sense to add an options column which would just be a comma
>separated string?
>Not that I have future options in mind but seems like something that might
>come up in the future.
>

I'd just add a boolean column to the catalog. That's what I did in the
patch adding support for streaming in-progress transactions. I don't think
we expect many additional parameters, so it makes little sense to optimize
for that case.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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