(pre-define dg-id-t b64
  dg-ordinal-t b32
  dg-id-max UINT64_MAX
  ;data can not be greater than lmdb max keysize, which is 511 by lmdb default but can be adjusted with recompiling lmdb
  dg-size-octets-data-max 511
  dg-size-octets-data-min 1
  dg-size-octets-id (sizeof dg-id-t) dg-size-octets-ordinal (sizeof dg-ordinal-t))

(pre-define (dg-id-equal? a b) (= a b))
(pre-define (dg-id-compare a b) (if* (< a b) -1 (> a b)))
(pre-define (dg-pointer->id a index) (deref (+ index (convert-type a dg-id-t*))))