Monitor and analyze all query activity: live execution, historical logs, failures, resource cost, thread-level breakdown, and per-user process summaries.

What it does

The Queries feature covers the full lifecycle of query observability:

• Live — what is running right now, elapsed time, memory, thread count.
• History — finished queries with full metrics (CPU, memory, read/write rows and bytes, duration).
• Failures — queries that errored, with error codes and messages.
• Cost — top queries by CPU, duration, or memory over a selected time window.
• Thread & parallelization — per-thread breakdown of a single query execution.
• Materialized view log — how each materialized view was triggered and how long it took.
• User processes — aggregated per-user resource usage from live processes.
• Query metric log — per-query resource samples taken throughout a query’s lifetime.

The Explain page does not query a log table; it runs EXPLAIN statements against the connected host interactively.

Pages

Permissions & access

All query pages fall under the queries feature id:

## Gate the whole feature to authenticated users
CHM_FEATURE_QUERIES_ACCESS=authenticated

## Disable the whole feature
CHM_FEATURE_QUERIES_ENABLED=false
## or
CHM_DISABLED_FEATURES=queries

## CHM_CONFIG_FILE (TOML)
[features.queries]
access = "authenticated"

When disabled, all sub-routes are removed from the nav and return a disabled screen on direct visit.

Configuration

No feature-specific configuration beyond the global query settings:

CLICKHOUSE_MAX_EXECUTION_TIME=60   # per-query timeout in seconds
NEXT_QUERY_CACHE_TTL=3600          # server-side cache TTL in seconds

Notes & limitations

• Kill action — the kill-query button on /running-queries issues KILL QUERY. The ClickHouse user configured via CLICKHOUSE_USER must have the KILL QUERY privilege. Without it, the button returns an error.
• system.query_log — ClickHouse writes to query_log asynchronously. Very recent queries (< a few seconds old) may not appear in history pages yet. Log retention and flush intervals are controlled by ClickHouse server config (query_log.flush_interval_milliseconds, query_log.ttl), not by chmonitor.
• system.query_views_log — only populated if <query_views_log> is enabled in the ClickHouse server config. The page shows an empty state or a table-not-found notice if it is absent.
• system.query_thread_log — requires <query_thread_log> to be enabled in ClickHouse config. Disabled by default on many installations.
• system.user_processes — available since ClickHouse 22.6. Earlier versions will show a table-not-found notice.
• system.query_metric_log — requires <query_metric_log> to be enabled in ClickHouse config. High-cardinality on busy clusters; enable with care.
• system.errors — the Common Errors view reads system.errors, which is always present and contains aggregated error-code counts (not per-query).

Related

• Authentication
• Settings reference
• Operations (merges & mutations)