If a query has a large number of joins, the planning time and space grows exponentially in N, the number of joins. About about N=8 it is not possible to plan a query exhaustively.
`LoptOptimizeJoinRule` is a heuristic join rule that uses a greedy algorithm. It operates on a `MultiJoinRel`, which must first have been created using `ConvertMultiJoinRule`. Enabling this rule, and disable the join transformation rules `SwapJoinRule` and `PushJoinThroughJoinRule`, it is possible to plan queries with N=60 and higher.