Dynamically setting __tablename__ for sharding in SQLAlchemy?

Question

In order to handle a growing database table, we are sharding on table name. So we could have database tables that are named like this:

table_md5one
table_md5         


        

Answer 1

OK, we went with the custom SQLAlchemy declaration rather than the declarative one.

So we create a dynamic table object like this:

from sqlalchemy import MetaData, Table, Column

def get_table_object(self, md5hash):
    metadata = MetaData()
    table_name = 'table_' + md5hash
    table_object = Table(table_name, metadata,
        Column('Column1', DATE, nullable=False),
        Column('Column2', DATE, nullable=False)
    )
    clear_mappers()
    mapper(ActualTableObject, table_object)
    return ActualTableObject

Where ActualTableObject is the class mapping to the table.