> ## Documentation Index
> Fetch the complete documentation index at: https://clickhouse.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# query_profiler_* session settings

> ClickHouse session settings in the query_profiler_* generated group.

export const SettingsInfoBlock = ({type, default_value, changeable_without_restart}) => {
  return <div className="not-prose" style={{
    display: "flex",
    flexWrap: "wrap",
    alignItems: "baseline",
    columnGap: "0.5rem",
    rowGap: "0.125rem",
    margin: "0.375rem 0",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <div style={{
    fontWeight: 600,
    opacity: 0.72
  }}>Type</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{type}</div>
      <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>Default</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{default_value}</div>
      {changeable_without_restart && <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>
          Changeable without restart
        </div>}
      {changeable_without_restart && <div style={{
    overflowWrap: "anywhere"
  }}>
          {changeable_without_restart}
        </div>}
    </div>;
};

These settings are available in [system.settings](/docs/reference/system-tables/settings) and are autogenerated from [source](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp).

<h2 id="query_profiler_cpu_time_period_ns">
  query\_profiler\_cpu\_time\_period\_ns
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000000000" />

Sets the period for a CPU clock timer of the [query profiler](/docs/concepts/features/performance/troubleshoot/sampling-query-profiler). This timer counts only CPU time.

Possible values:

* A positive integer number of nanoseconds.

  Recommended values:

  * 10000000 (100 times a second) nanoseconds and more for single queries.
  * 1000000000 (once a second) for cluster-wide profiling.

* 0 for turning off the timer.

See also:

* System table [trace\_log](/docs/reference/system-tables/trace_log)

<h2 id="query_profiler_real_time_period_ns">
  query\_profiler\_real\_time\_period\_ns
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000000000" />

Sets the period for a real clock timer of the [query profiler](/docs/concepts/features/performance/troubleshoot/sampling-query-profiler). Real clock timer counts wall-clock time.

Possible values:

* Positive integer number, in nanoseconds.

  Recommended values:

  * 10000000 (100 times a second) nanoseconds and less for single queries.
  * 1000000000 (once a second) for cluster-wide profiling.

* 0 for turning off the timer.

See also:

* System table [trace\_log](/docs/reference/system-tables/trace_log)

Cloud default value: `3000000000`.