This is the implementation of the ClickHouse data handler for MindsDB. ClickHouse is a column-oriented database management system (DBMS) for online analytical processing of queries (OLAP).

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Prerequisites

Before proceeding, ensure the following prerequisites are met:
  1. Install MindsDB locally via Docker or use MindsDB Cloud.
  2. To connect ClickHouse to MindsDB, install the required dependencies following this instruction.
  3. Install or ensure access to ClickHouse.

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Implementation

This handler was implemented using the standard clickhouse-sqlalchemy library. The required arguments to establish a connection are as follows:
  • host is the hostname or IP address of the ClickHouse server.
  • port is the TCP/IP port of the ClickHouse server.
  • user is the username used to authenticate with the ClickHouse server.
  • password is the password to authenticate the user with the ClickHouse server.
  • database defaults to default. It is the database name to use when connecting with the ClickHouse server.
  • protocol defaults to native. It is an optional parameter. Its supported values are http and https.

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Usage

In order to make use of this handler and connect to the ClickHouse database in MindsDB, the following syntax can be used: 
CREATE DATABASE clickhouse_datasource
WITH
    engine = 'clickhouse',
    parameters = {
      "host": "127.0.0.1",
      "port": "9000",
      "user": "root",
      "password": "password",
      "database": "test_db"
    };
You can use this established connection to query your table as follows: 
SELECT *
FROM clickhouse_datasource.example_table;
If you want to switch to a different database instead of the one you have connected, you can include it in the query as:
SELECT *
FROM clickhouse_datasource.new_database.example_table;