ClickHouse

Plugin: go.d.plugin Module: clickhouse

Overview

This collector retrieves performance data from ClickHouse for connections, queries, resources, replication, IO, and data operations (inserts, selects, merges) using HTTP requests and ClickHouse system tables. It monitors your ClickHouse server's health and activity.

It sends HTTP requests to the ClickHouse HTTP interface, executing SELECT queries to retrieve data from various system tables. Specifically, it collects metrics from the following tables:

• system.metrics
• system.async_metrics
• system.events
• system.disks
• system.parts
• system.processes

This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.

Default Behavior

Auto-Detection

By default, it detects ClickHouse instances running on localhost that are listening on port 8123. On startup, it tries to collect metrics from:

• http://127.0.0.1:8123

Limits

The default configuration for this integration does not impose any limits on data collection.

Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.

Setup

You can configure the clickhouse collector in two ways:

:::important

UI configuration requires paid Netdata Cloud plan.

:::

Prerequisites

No action required.

Configuration

Options

The following options can be defined globally: update_every, autodetection_retry.

via UI

Configure the clickhouse collector from the Netdata web interface:

1. Go to Nodes.
2. Select the node where you want the clickhouse data-collection job to run and click the :gear: (Configure this node). That node will run the data collection.
3. The Collectors → Jobs view opens by default.
4. In the Search box, type clickhouse (or scroll the list) to locate the clickhouse collector.
5. Click the + next to the clickhouse collector to add a new job.
6. Fill in the job fields, then click Test to verify the configuration and Submit to save.
   • Test runs the job with the provided settings and shows whether data can be collected.
   • If it fails, an error message appears with details (for example, connection refused, timeout, or command execution errors), so you can adjust and retest.

via File

The configuration file name for this integration is go.d/clickhouse.conf.

The file format is YAML. Generally, the structure is:

update_every: 1
autodetection_retry: 0
jobs:
  - name: some_name1
  - name: some_name2

You can edit the configuration file using the edit-config script from the Netdata config directory.

cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/clickhouse.conf

Examples

Basic

A basic example configuration.

jobs:
  - name: local
    url: http://127.0.0.1:8123

HTTP authentication

Basic HTTP authentication.

jobs:
  - name: local
    url: http://127.0.0.1:8123
    username: username
    password: password

HTTPS with self-signed certificate

ClickHouse with enabled HTTPS and self-signed certificate.

jobs:
  - name: local
    url: https://127.0.0.1:8123
    tls_skip_verify: yes

Multi-instance

Note: When you define multiple jobs, their names must be unique.

Collecting metrics from local and remote instances.

jobs:
  - name: local
    url: http://127.0.0.1:8123

  - name: remote
    url: http://192.0.2.1:8123

Alerts

The following alerts are available:

Metrics

Metrics grouped by scope.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.

Per ClickHouse instance

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

Per disk

These metrics refer to the Disk.

Labels:

Metrics:

Per table

These metrics refer to the Database Table.

Labels:

Metrics:

Live Data

This collector exposes real-time functions for interactive troubleshooting in the Live tab.

Top Queries

Retrieves and aggregates SQL query performance metrics from ClickHouse system.query_log table.

This function queries the system.query_log table, which contains information about executed queries including timing, resource usage, and execution statistics. Queries are grouped by their normalized hash (normalized_query_hash) to aggregate statistics for identical query patterns with different literal values.

Use cases:

• Identify slow queries that consume the most execution time
• Find frequently executed queries that may benefit from optimization
• Analyze I/O patterns by examining read/written rows and bytes

Query text is truncated at 4096 characters for display purposes.

Prerequisites

Grant access to system.query_log

Ensure the Netdata user can read system.query_log on the target ClickHouse instance.

1. Verify query_log is enabled (enabled by default):

   sqlCopy

   SELECT * FROM system.query_log LIMIT 1;
   

2. If using a dedicated monitoring user, grant SELECT access:

   sqlCopy

   GRANT SELECT ON system.query_log TO netdata_user;
   

:::info

• The query_log table is enabled by default in ClickHouse
• Only queries with type='QueryFinish' are included in the results
• The normalized_query_hash column is used for grouping when available

:::

Parameters

Returns

Aggregated query statistics from system.query_log, grouped by normalized query hash. Each row represents a unique query pattern with cumulative metrics across all executions.

Troubleshooting

Debug Mode

Important: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.

To troubleshoot issues with the clickhouse collector, run the go.d.plugin with the debug option enabled. The output should give you clues as to why the collector isn't working.

• Navigate to the plugins.d directory, usually at /usr/libexec/netdata/plugins.d/. If that's not the case on your system, open netdata.conf and look for the plugins setting under [directories].

  bashCopy

  cd /usr/libexec/netdata/plugins.d/
  

• Switch to the netdata user.

  bashCopy

  sudo -u netdata -s
  

• Run the go.d.plugin to debug the collector:

  bashCopy

  ./go.d.plugin -d -m clickhouse
  

  To debug a specific job:

  bashCopy

  ./go.d.plugin -d -m clickhouse -j jobName
  

Getting Logs

If you're encountering problems with the clickhouse collector, follow these steps to retrieve logs and identify potential issues:

• Run the command specific to your system (systemd, non-systemd, or Docker container).
• Examine the output for any warnings or error messages that might indicate issues. These messages should provide clues about the root cause of the problem.

System with systemd

Use the following command to view logs generated since the last Netdata service restart:

journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep clickhouse

System without systemd

Locate the collector log file, typically at /var/log/netdata/collector.log, and use grep to filter for collector's name:

grep clickhouse /var/log/netdata/collector.log

Note: This method shows logs from all restarts. Focus on the latest entries for troubleshooting current issues.

Docker Container

If your Netdata runs in a Docker container named "netdata" (replace if different), use this command:

docker logs netdata 2>&1 | grep clickhouse