0382 — Partition batches use plain DROP TABLE IF EXISTS with no DETACH first

Context. The designed fix for topic.Destroy lock exhaustion was worded as “batched DETACH + DROP per partition.” Implementing it raised the question of whether detaching before dropping actually buys anything.

Decision. dropPartitionBatch does a plain DROP TABLE IF EXISTS per partition with no detach. A non-concurrent DETACH takes the exact same ACCESS EXCLUSIVE lock on the parent that the DROP does, so detaching first is the same locks in two statements instead of one.

Consequences. One statement per partition, half the lock acquisitions of the two-step shape. Rejected: DETACH CONCURRENTLY — cannot run inside a transaction block and leaves pending-detach states that would complicate crash resume.