I'm coming around to the idea that the fact that you can cancel the wait phase of DETACH CONCURRENTLY creates quite a disaster, and it's not easy to get away from it. The idea that REPEATABLE READ mode means that you now see detached partitions as if they were in normal condition, is completely at odds with that behavior.
I think a possible solution to this problem is that the "detach" flag in pg_inherits is not a boolean anymore, but an Xid (or maybe two Xids). Not sure exactly which Xid(s) yet, and I'm not sure what are the exact rules, but the Xid becomes a marker that indicates an horizon past which the partition is no longer visible. Then, REPEATABLE READ can see the partition, but only if its snapshot is older than the Xid. -- Álvaro Herrera Valdivia, Chile "La persona que no quería pecar / estaba obligada a sentarse en duras y empinadas sillas / desprovistas, por cierto de blandos atenuantes" (Patricio Vogel)
