Sorry, it's not about querying. I am implementing an invalidation mechanism for Postgres Query Cache as part of my masters project. In order to this, I need to store details(like name) of each table the query uses. In essence, I need to store the table names of the cached queries.
Initially, I thought of writing a code that could extract the table names but later discovered that it is a gargantuan task as I shall have to include around 600 production rules as was hinted in a Stackoverflow Exchange post. Hence, I thought of getting hold of the data structure used for storing table names of a DB but I couldn't get it.
Its a Ruby-based library that makes the Postgres parser easier to access from the outside, getting a list of tables from a query is trivial - but if you need the oids you'll have to do it like pgpool does.