[HACKERS] How does postgres store the join predicate for a relation in a given query

Hi all,

When you fire a query in postgresql, it will first parse the query and create the data structures for storing various aspects of the query and executing the query. (Like RangeTblEntry, PlannerInfo, RangeOptInfo etc.).

I want to know how does postgresql stores the join predicates of a query. Like which data structure is used to store the join predicates.

How can we find the join predicates applied on a relation from relid, Oid or RangeTblEntry ?

I want to construct a join graph for a given query, for which I need the join predicates between two relations.