chmonitorOverview
Read cluster health at a glance — active queries, memory, disk, and CPU pulled live from ClickHouse system tables.
The Overview page is where each ClickHouse host lands you: instant health status, active queries, memory, disk, and CPU at a glance.
| Routes | /overview |
| Feature id | overview |
| Default access | public |
| Requires auth | No (set CHM_FEATURE_OVERVIEW_ACCESS=authenticated to gate) |
| System tables | system.asynchronous_metrics, system.metrics, system.processes, system.disks, system.tables |
| ClickHouse grants | SELECT on the system tables above |
What it does
Overview pulls live numbers from several system tables to answer, at a glance:
- Is the server healthy right now?
- How many queries are running?
- How much memory and disk are in use?
- What is CPU load?
The page auto-refreshes on a short interval. It issues no write operations.
Using it
The page groups its live signals into five tabs.
Active TCP and HTTP connections, connection pool usage, and rejected connections over time.
Running query count, queries-per-second rate, and current memory consumed by queries.
Active merge count, parts waiting to merge, and merge throughput (rows/s, bytes/s).
Replication queue depth and absolute delay across all replicated tables on this host. Only meaningful when replicated tables exist.
CPU load (from system.asynchronous_metrics), memory usage, uptime, and OS-level stats.
| Page | Route | What it shows | System tables |
|---|---|---|---|
| Overview | /overview | CPU, memory, disk gauges; active query count; connection count; replication lag indicator | system.asynchronous_metrics, system.metrics, system.processes, system.disks, system.tables |
Data freshness and behavior
system.asynchronous_metricsvalues are recalculated by ClickHouse on a background interval (default ~1 s). The values shown are as fresh as that interval allows.system.disksreports the disks ClickHouse knows about. If you use multiple storage policies or remote disks (S3, HDFS), all configured disks appear.system.tablesis queried to derive a table count. On clusters with many databases this can be slow; increaseCLICKHOUSE_MAX_EXECUTION_TIMEif overviews time out.- The Replication tab shows replication lag only when replicated tables exist on the host. The tab still appears even if there are none.
Permissions & access
Overview is public by default. To restrict it:
CHM_FEATURE_OVERVIEW_ACCESS=authenticated[features.overview]
access = "authenticated"To disable the feature entirely:
CHM_DISABLED_FEATURES=overview
CHM_FEATURE_OVERVIEW_ENABLED=falseWhen disabled, the route is removed from the nav and a disabled screen is shown on direct visit.
There is no feature-specific configuration. The refresh interval and caching behaviour follow the global query settings:
CLICKHOUSE_MAX_EXECUTION_TIME=60 # query timeout in seconds