Quickstart¶
This page gives a good introduction to clickhouse-sqlalchemy. It assumes you already have clickhouse-sqlalchemy installed. If you do not, head over to the Installation section.
It should be pointed that session must be created with
clickhouse_sqlalchemy.make_session
. Otherwise session.query
and
session.execute
will not have ClickHouse SQL extensions. The same is
applied to Table
and get_declarative_base
.
Let’s define some table, insert data into it and query inserted data.
from sqlalchemy import create_engine, Column, MetaData from clickhouse_sqlalchemy import ( Table, make_session, get_declarative_base, types, engines ) uri = 'clickhouse+native://localhost/default' engine = create_engine(uri) session = make_session(engine) metadata = MetaData(bind=engine) Base = get_declarative_base(metadata=metadata) class Rate(Base): day = Column(types.Date, primary_key=True) value = Column(types.Int32) __table_args__ = ( engines.Memory(), ) # Emits CREATE TABLE statement Rate.__table__.create()
Now it’s time to insert some data
from datetime import date, timedelta from sqlalchemy import func today = date.today() rates = [ {'day': today - timedelta(i), 'value': 200 - i} for i in range(100) ]
Let’s query inserted data
session.execute(Rate.__table__.insert(), rates) session.query(func.count(Rate.day)) \ .filter(Rate.day > today - timedelta(20)) \ .scalar()
Now you are ready to configure your connection and see more ClickHouse features support.