Citus: Distributed PostgreSQL for Data-Intensive Applications paper can be downloaded here.
Recently, our team got a request to provide a solution to shard Postgres. One of the solutions that we discussed was Citus. I have heard about the product and seen their blogs related to Postgres in the past but never used it. I thought it would be fun to read about its internal workings.
If you find something wrong on the notes, please send a pull request.