Disabling options lowers the estimated cost of a query

Hi,

I want to examine the exhaustive search and not the geqo here. I'd expect the exhaustive search to give the plan with the lowest cost, but apparently it doesn't. I have found a few dozen different querys where that isn't the case. I attached one straight forward example. For the join of two partitions a row first approach would have been reasonable.

Please note that I have enable_partitionwise_join on.

Both tables are partitioned by si, agv and have a primary key leading with si, agv.

I know that for this particular query the planning time dominates the execution time, but that is not my issue here. It's more a synthetic boiled down example coming from a more complex one with notably higher execution time.

Thank you for having a look!

Regards

Arne