sqlalchemy-postgres-copy is a utility library that wraps the PostgreSQL COPY command for use with SQLAlchemy. The COPY command offers performant exports from PostgreSQL to TSV, CSV, or binary files, as well as imports from files to PostgresSQL tables. Using COPY is typically much more efficient than importing and exporting data using Python.

pip install -U sqlalchemy-postgres-copy

import postgres_copy
from models import Album, session, engine

# Export a CSV containing all Queen albums
query = session.query(Album).filter_by(artist='Queen')
with open('/path/to/file.csv', 'w') as fp:
    postgres_copy.copy_to(query, fp, engine, format='csv', header=True)

# Import a tab-delimited file
with open('/path/to/file.tsv') as fp:
    postgres_copy.copy_from(fp, Album, engine)