hstore note - fengggli/comanche GitHub Wiki
- map and map_keys will use open_pool_t->map, which is defined either in hstore_pmem or hstore_nupm namespaces.
- /hstore/src/hop_hash.h
- it can use different allocators ()
- hstore, uses hop-scotch map: http://mcg.cs.tau.ac.il/papers/disc2008-hopscotch.pdf