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Databases
Direct usage of Database objects is not expected in this library. But in some cases, you may still need them.
This section describes Database objects and there usage.
django_clickhouse.database.Database is a class, describing a ClickHouse database connection.
Getting database objects
To get a Database object by its alias name in CLICKHOUSE_DATABASES
use django_clickhouse.database.connections object.
This object is a django_clickhouse.database.ConnectionProxy instance:
it creates Database objects when they are used for the first time and stores them in memory.
Example:
from django_clickhouse.database import connections
# Database objects are inited on first call
db = connections['default']
secondary = connections['secondary']
# Already inited - object is returned from memory
db_link = connections['default']
Database object
Database class is based on infi.clickhouse_orm Database object, but extends it with some extra attributes and methods:
Database migrations are restricted
I expect this library migration system to be used. Direct database migration will lead to migration information errors.
insert_tuples and select_tuples methods
infi.clickhouse_orm store data rows in Model objects.
It works well on hundreds of records.
But when you sync 100k records in a batch, initializing 100k model instances will be slow.
Too optimize this process ClickHouseModel class have get_tuple_class() method.
It generates a namedtuple class,
with same data fields a model has.
Initializing such tuples takes much less time, then initializing Model objects.