from sqlalchemy import create_engine

# Port 5439 for Redshift
engine = create_engine("postgresql://user@localhost:5432/mydb")
df = pd.read_sql_query("select * from airlines", engine)

# Get results in chunks
for chunk in pd.read_sql_query("select * from airlines", engine, chunksize=5):
    print(chunk)

# Writing back
df.to_sql(
    "table"
    schema="schema"
    # fail, replace or append
    if_exists="append",
    # write back in chunks
    chunksize = 10000
)