Re: [HACKERS] Built-in plugin for logical decoding output

On 23/09/17 00:28, Gregory Brail wrote:

We have been working on a project that makes extensive use of logical replication for use inside Apigee (which is a very small part of Google):

https://github.com/apigee-labs/transicator

In order to do this, we had to write our own logical replication plugin because the supplied "test_decoding" plugin from the "contrib" directory was hard for us to work with. Primarily:

1) It doesn't include all the fields that we need for Transicator (most importantly we need the LSN and the 64-bit transaction ID).
2) It outputs a text format that is hard to parse.

I imagine that other users of logical decoding are facing similar problems.

Would the community support the development of another plugin that is distributed as part of "contrib" that addresses these issues? I'd be happy to submit a patch, or GitHub repo, or whatever works best as an example. (Also, although Transicator uses protobuf, I'm happy to have it output a simple binary format as well.)

As a side note, doing this would also help making logical decoding a useful feature for customers of Amazon and Google's built-in Postgres hosting options. In those environments, there's no way to add a custom plugin to Postgres, so anything not built in the product tends to be harder for someone to consume.

If anyone is interested in looking more:

The plugin code is here:
https://github.com/apigee-labs/transicator/tree/master/pgoutput

and produces output defined by the "ChangePb" structure defined here:
https://github.com/apigee-labs/transicator/blob/master/common/transicator.proto

    How about using pgoutput, which is included by default in PostgreSQL 10, as the basis for logical replication?


    Cheers,

    Álvaro


--

Alvaro Hernandez


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