ClickHouse Writer (Docker)

The ClickHouse Writer (Docker) component writes data into a ClickHouse database using a TCP connection. Authentication is handled with a username and password (or other supported mechanisms). It supports configurable save modes and column filtering for selective writes.

Configuration Sections

The ClickHouse Writer configurations are organized into the following sections:

  • Basic Information

  • Meta Information

  • Resource Configuration

  • Connection Validation

Meta Information Tab

Parameter
Description
Example

Host IP Address

Host IP address of the ClickHouse server.

192.168.1.50

Port

TCP port for ClickHouse.

9000

Username

Username for authentication.

default

Password

Password for the database user.

********

Database Name

Target database name.

analytics_db

Table Name

Single or multiple table names. Use commas (,) to separate multiple tables.

orders, customers

Settings

Optional configuration settings for query execution.

max_threads=4

Enable SSL

Enables SSL for secure communication with the ClickHouse server.

true

Save Mode

Defines write behavior. Options: Append.

Append

Column Filter

Select specific columns, rename them with aliases, and define their types.

See Column Filtering.

Save Mode

  • Append

    • Adds new records into the specified ClickHouse table(s).

    • When Append is selected in ClickHouse Writer (Docker) or Data Sync (ClickHouse driver), the table is created in the database with the Memory engine.

⚠️ Note: The Docker-based ClickHouse Writer supports only TCP port (9000) and Append as the save mode.

Column Filtering

The Column Filter section allows users to control which columns are written.

Field
Description
Example

Name

Column name from upstream data.

customer_id

Alias

Alias name for the column in ClickHouse.

cust_id

Column Type

Data type of the column.

String

Additional Options:

  • Upload File: Upload a schema file in CSV/JSON format (≤2 MB) to auto-populate columns.

  • Download Data: Export schema in JSON format.

  • Delete Data: Clear all column filter mappings.

Notes

  • Save Mode Limitation: Only Append is supported in the Docker-based ClickHouse Writer.

  • Table Engine: Tables created with Append use the Memory engine, meaning data is not persisted after server restarts. For persistence, configure table engines directly in ClickHouse (e.g., MergeTree).

  • SSL: Recommended for secure communication in production environments.

  • Ensure target tables exist in the database before activating the pipeline.

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