description	ClickHouse Data Connector Documentation

ClickHouse Data Connector

ClickHouse is a fast, open-source columnar database management system designed for online analytical processing (OLAP) and real-time analytics. This connector enables federated SQL queries from a ClickHouse server.

datasets:
  - from: clickhouse:my.dataset
    name: my_dataset

Configuration

`from`

The from field for the ClickHouse connector takes the form of from:db.dataset where db.dataset is the path to the Dataset within ClickHouse. In the example above it would be my.dataset.

If db is not specified in either the from field or the clickhouse_db parameter, it will default to the default database.

{% hint style="info" %} Unquoted identifiers are normalized to lowercase. To reference a table or database with mixed-case characters, wrap each case-sensitive part in double quotes: clickhouse:my_db."MixedCaseTable". See Identifier Case Sensitivity. {% endhint %}

`name`

The dataset name. This will be used as the table name within Spice.

datasets:
  - from: clickhouse:my.dataset
    name: cool_dataset

SELECT COUNT(*) FROM cool_dataset;

+----------+
| count(*) |
+----------+
| 6001215  |
+----------+

The dataset name cannot be a reserved keyword or any of the following keywords that are reserved by ClickHouse:

PREWHERE
SETTINGS
FORMAT

`params`

The ClickHouse data connector can be configured by providing the following params:

Parameter Name	Definition
`clickhouse_connection_string`	The connection string to use to connect to the ClickHouse server. This can be used instead of providing individual connection parameters.
`clickhouse_host`	The hostname of the ClickHouse server.
`clickhouse_tcp_port`	The port of the ClickHouse server.
`clickhouse_db`	The name of the database to connect to.
`clickhouse_user`	The username to connect with.
`clickhouse_pass`	The password to connect with.
`clickhouse_secure`	Optional. Specifies the SSL/TLS behavior for the connection, supported values: `true` (default) - requires an SSL connection, `false` - does not use SSL.
`connection_timeout`	Optional. Specifies the connection timeout in milliseconds.

Examples

Connecting to localhost

datasets:
  - from: clickhouse:my.dataset
    name: my_dataset
    params:
      clickhouse_host: localhost
      clickhouse_tcp_port: 9000
      clickhouse_db: my_database
      clickhouse_user: my_user
      clickhouse_pass: ${secrets:my_clickhouse_pass}
      connection_timeout: 10000
      clickhouse_secure: false

Specifying a connection timeout

datasets:
  - from: clickhouse:my.dataset
    name: my_dataset
    params:
      clickhouse_connection_string: tcp://my_user:${secrets:my_clickhouse_pass}@localhost:9000/my_database
      connection_timeout: 10000
      clickhouse_secure: true

Using a connection string

datasets:
  - from: clickhouse:my.dataset
    name: my_dataset
    params:
      clickhouse_connection_string: tcp://my_user:${secrets:my_clickhouse_pass}@localhost:9000/my_database?connection_timeout=10000&secure=true

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