FYI: jOOQ blog

​If you want to know how PostgreSQL compares to other databases, or are
looking for ideas on areas to improve, the jOOQ blog looks like a good
resource: https://blog.jooq.org/. jOOQ is a java library that provides a
database-agnostic way to access many different types of databases. I know
it does some query optimizations but I don't know how advanced it is. The
other reason for them to track advanced functionality available in some
databases is to ensure that they support users who want to use those
features.

Most of the blog is specific to java or its library but there's also
frequent articles on advanced functionality (row values, window functions,
etc.), query optimization, and comparisons between the databases. The
comparisons of query optimizations in particular might be good low hanging
fruit since it doesn't involve any user-facing changes, just recognizing a
few additional patterns in the query parse tree and knowing a more
efficient way to perform equivalent work.

Bear