System Models

Clickhouse docs.

System models are read only models for implementing part of the system’s functionality, and for providing access to information about how the system is working.

Currently the following system models are supported:

Class	DB Table	Comments
SystemPart	system.parts	Gives methods to work with partitions. See below.

Partitions and Parts

ClickHouse docs.

A partition in a table is data for a single calendar month. Table “system.parts” contains information about each part.

Method	Parameters	Comments
get(static)	database, conditions=””	Gets database partitions, filtered by conditions
get_active(static)	database, conditions=””	Gets only active (not detached or dropped) partitions, filtered by conditions
detach	settings=None	Detaches the partition. Settings is a dict of params to pass to http request
drop	settings=None	Drops the partition. Settings is a dict of params to pass to http request
attach	settings=None	Attaches already detached partition. Settings is a dict of params to pass to http request
freeze	settings=None	Freezes (makes backup) of the partition. Settings is a dict of params to pass to http request
fetch	settings=None	Fetches partition. Settings is a dict of params to pass to http request

Usage example:

from clickhouse_orm import Database, SystemPart
db = Database('my_test_db', db_url='http://192.168.1.1:8050', username='scott', password='tiger')
partitions = SystemPart.get_active(db, conditions='')  # Getting all active partitions of the database
if len(partitions) > 0:
    partitions = sorted(partitions, key=lambda obj: obj.name)  # Partition name is YYYYMM, so we can sort so
    partitions[0].freeze()  # Make a backup in /opt/clickhouse/shadow directory
    partitions[0].drop()  # Dropped partition

Note: system.parts stores information for all databases. To be correct, SystemPart model was designed to receive only parts belonging to the given database instance.