demo.py

import lmdb

def test():

    env = lmdb.open("test.lmdb", max_dbs=1, map_size=15*1024*1024)
    try:
        value = bytearray(" "*9*1024*1024)

        with env.begin(write=True, buffers=True) as txn:
            txn.put("big", value, dupdata=False, overwrite=True)

        with env.begin(write=True,) as txn:
            print txn.delete("big")

        with env.begin(write=True,) as txn:
            txn.put('a', 'a')

        with env.begin(write=True, buffers=True) as txn:
            txn.put("big", value, dupdata=False, overwrite=True)

        with env.begin(write=True,) as txn:
            print txn.delete("big")

        with env.begin(write=True,) as txn:
            txn.put('a', 'a')

    finally:
        env.sync()
        env.close()
        #import pdb;pdb.set_trace()

if __name__ == "__main__":
    test()