Tag: Database

Defining Multi-Column Indexes Using ORM Declarative Mapping

from sqlalchemy import create_engine, Column, Integer, String, Index
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

engine = create_engine('postgresql://username:password@localhost/mydatabase')
Base = declarative_base()

class Employee(Base):
    __tablename__ = 'employees'
    id = Column(Integer, primary_key=True)
    last_name = Column(String)
    first_name = Column(String)
    department_id = Column(Integer)

    __table_args__ = (
        Index('idx_employees_last_first', 'last_name', 'first_name'),
    )

Base.metadata.create_all(engine)

Creating Indexes After Table Definition

from sqlalchemy import create_engine, MetaData, Table, Index

engine = create_engine('postgresql://username:password@localhost/mydatabase')
metadata = MetaData(bind=engine)

# Reflect the existing table
employees = Table('employees', metadata, autoload_with=engine)

# Create the index
index = Index('idx_employees_last_first', employees.c.last_name, employees.c.first_name)
index.create(engine)

References
https://stackoverflow.com/questions/14419299/adding-indexes-to-sqlalchemy-models-after-table-creation