ClickHouse

Zequel supports ClickHouse, a column-oriented database designed for online analytical processing (OLAP). ClickHouse is optimized for fast reads over large datasets.

Supported versions: ClickHouse 22.8 – Latest

Connection Setup

To connect to a ClickHouse instance, provide the following details:

Field	Description	Default
Host	Server hostname or IP address	localhost
Port	HTTP interface port	8123
User	Database user	default
Password	User password	--
Database	Target database name	default

Connection Protocols

ClickHouse exposes two interfaces:

Protocol	Default Port	Description
HTTP	8123	Used by Zequel for connections. Widely compatible and firewall-friendly.
Native	9000	ClickHouse native binary protocol. Used by the ClickHouse CLI and some drivers.

Zequel connects to ClickHouse over the HTTP interface on port 8123 by default.

SSH Tunnels

You can connect to remote ClickHouse instances through an SSH tunnel. Configure the SSH host, port, user, and authentication method (password or private key) in the connection dialog.

SSL / TLS

Zequel supports SSL/TLS connections to ClickHouse. You can provide a CA certificate, client certificate, and client key to establish a secure connection. When using SSL, the default HTTP port is typically 8443.

Supported Features

Tables and Columns

Browse and inspect tables and their columns. ClickHouse uses a variety of table engines (MergeTree, ReplacingMergeTree, etc.) that determine how data is stored and queried. The data grid provides browsing, sorting, and filtering.

Views

View and inspect standard ClickHouse views.

Process Monitor

View active queries and their resource usage. Useful for identifying slow or resource-intensive queries in an analytical workload.

ClickHouse-Specific Notes

• Table Engines -- ClickHouse tables are backed by different engines (MergeTree family, Log family, etc.). The engine determines storage behavior, indexing, and replication. Zequel displays the engine type for each table.
• Approximate Counts -- Row counts in ClickHouse may be approximate depending on the table engine, as exact counts can be expensive on large datasets.
• No Foreign Keys -- ClickHouse does not support foreign key constraints. Data integrity is managed at the application level.
• No Traditional Indexes -- ClickHouse uses primary keys and data skipping indexes rather than B-tree indexes found in relational databases.

Limitations

The following features are not available for ClickHouse:

• Foreign Keys -- Not supported by ClickHouse.
• Traditional Indexes -- ClickHouse uses its own indexing mechanisms.
• Routines / Triggers -- Not supported by ClickHouse.
• Events -- Not supported by ClickHouse.
• ER Diagrams -- Not available due to the lack of foreign key relationships.
• Users -- Not managed through Zequel for ClickHouse.

Tools

Query Editor

Write and execute SQL queries with syntax highlighting, autocompletion, and result display in the data grid. ClickHouse supports standard SQL with extensions for analytical functions.

Process Monitor

Monitor running queries and their resource consumption.

Data Operations

• Browse -- View table data in a paginated data grid.
• Edit -- Modify cell values directly in the data grid.
• Import -- Load data into tables from external files.
• Export -- Export query results or table data to various formats.