Distributed, durable MemoryStore over Mnesia, in an :ordered_set table with attributes [:key, :value]: one row per document ({namespace, path} → the document) plus one totals row per namespace ({namespace, 0} → {bytes, documents}). Every operation is one :mnesia.transaction/1. A write first takes the write lock on its namespace's totals row, so a namespace's writers run one at a time and compare-and-set, rename, delete_tree and the put/6 limits are atomic across the cluster. get/3 reads one row. list/3, delete_tree/3, rename/4 and delete_namespace/2 select the namespace's rows, which locks the whole table for the transaction (a read lock for list/3): a rename or tree delete in one namespace briefly holds writes in the others, and a list/3 waits for a write in progress in any namespace.

The handle is the table name. Create it with create_tables/1 (copies: :disc_copies by default, for durability; :table defaults to :normandy_memory_documents); new/1 makes a uniquely named ram_copies table for tests. A release using this store must include :mnesia in extra_applications.