row_count.py

from sqlalchemy import MetaData, Table, text
from sqlalchemy.orm import scoped_session
from sqlalchemy import create_engine, URL
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

connection_cred = {
    'username':'postgres',
    'password': '',
    'host':'',
    'database': ''
}
db_url = URL.create(
    "postgresql+psycopg2",
    **connection_cred
)
engine = create_engine(db_url)

session_factory = sessionmaker(bind=engine)
session = scoped_session(session_factory)
Base = declarative_base()
metadata = MetaData()
metadata.reflect(engine)

table_with_count = {}
for table in metadata.tables.values():
    table = Table(table.name, metadata, autoload=True, autoload_with=engine)
    select_query = table.select()

    with engine.connect() as conn:
        row_count = conn.execute(text('''SELECT COUNT(*) FROM "{}";'''.format(table.name))).scalar()
        table_with_count[table.name] = row_count

for key in sorted(table_with_count):
    print(key, table_with_count[key])