ZODB provides an object-oriented database for Python that provides
a high-degree of transparency. ZODB runs on Python 2.7 or Python 3.4
 and above. It also runs on PyPy.

*no separate language for database operations
*very little impact on your code to make objects persistent
*no database mapper that partially hides the database.
*Using an object-relational mapping is not like using an object-oriented
database.
*almost no seam between code and database.