A few years ago I wrote an experimental Logical Decoding plugin that translates database transactions to DNS UPDATE messages. I was super impressed by how nice it was coding to PostgreSQL's plugin APIs in C. I'm currently not sure if a C plugin is the best approach for this particular task: it might be better to use one of the more popular Logical Decoding to JSON plugins and munge the JSON into DNS UPDATEs in something more high-level than C.