Source code for examples.performance.bulk_updates
"""This series of tests illustrates different ways to UPDATE a large number
of rows in bulk.
"""
from . import Profiler
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, create_engine, bindparam
from sqlalchemy.orm import Session
Base = declarative_base()
engine = None
class Customer(Base):
__tablename__ = "customer"
id = Column(Integer, primary_key=True)
name = Column(String(255))
description = Column(String(255))
Profiler.init("bulk_updates", num=100000)
@Profiler.setup
def setup_database(dburl, echo, num):
global engine
engine = create_engine(dburl, echo=echo)
Base.metadata.drop_all(engine)
Base.metadata.create_all(engine)
s = Session(engine)
for chunk in range(0, num, 10000):
s.bulk_insert_mappings(Customer, [
{
'name': 'customer name %d' % i,
'description': 'customer description %d' % i
} for i in range(chunk, chunk + 10000)
])
s.commit()
@Profiler.profile
def test_orm_flush(n):
"""UPDATE statements via the ORM flush process."""
session = Session(bind=engine)
for chunk in range(0, n, 1000):
customers = session.query(Customer).\
filter(Customer.id.between(chunk, chunk + 1000)).all()
for customer in customers:
customer.description += "updated"
session.flush()
session.commit()