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_md5two table_md5three
All tables have the exact same schema.
How do we use SQLAlchemy and dynamically specify the tablename for the class that corresponds to this? Looks like the declarative_base() classes need to have tablename pre-specified.
There will eventually be too many tables to manually specify derived classes from a parent/base class. We want to be able to build a class that can have the tablename set up dynamically (maybe passed as a parameter to a function.)
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.
Answered By – Suman
Answer Checked By – Marie Seifert (BugsFixing Admin)