> ## 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.

# short_circuit_function_evaluation_* session settings

> ClickHouse session settings in the short_circuit_function_evaluation_* 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="short_circuit_function_evaluation">
  short\_circuit\_function\_evaluation
</h2>

<SettingsInfoBlock type="ShortCircuitFunctionEvaluation" default_value="enable" />

Allows calculating the [if](/docs/reference/functions/regular-functions/conditional-functions#if), [multiIf](/docs/reference/functions/regular-functions/conditional-functions#multiIf), [and](/docs/reference/functions/regular-functions/logical-functions#and), and [or](/docs/reference/functions/regular-functions/logical-functions#or) functions according to a [short scheme](https://en.wikipedia.org/wiki/Short-circuit_evaluation). This helps optimize the execution of complex expressions in these functions and prevent possible exceptions (such as division by zero when it is not expected).

Possible values:

* `enable` — Enables short-circuit function evaluation for functions that are suitable for it (can throw an exception or computationally heavy).
* `force_enable` — Enables short-circuit function evaluation for all functions.
* `disable` — Disables short-circuit function evaluation.

<h2 id="short_circuit_function_evaluation_for_nulls">
  short\_circuit\_function\_evaluation\_for\_nulls
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.1"},{"label": "1"},{"label": "Allow to execute functions with Nullable arguments only on rows with non-NULL values in all arguments"}]}]} />

Optimizes evaluation of functions that return NULL when any argument is NULL. When the percentage of NULL values in the function's arguments exceeds the short\_circuit\_function\_evaluation\_for\_nulls\_threshold, the system skips evaluating the function row-by-row. Instead, it immediately returns NULL for all rows, avoiding unnecessary computation.

<h2 id="short_circuit_function_evaluation_for_nulls_threshold">
  short\_circuit\_function\_evaluation\_for\_nulls\_threshold
</h2>

<SettingsInfoBlock type="Double" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.1"},{"label": "1"},{"label": "Ratio threshold of NULL values to execute functions with Nullable arguments only on rows with non-NULL values in all arguments. Applies when setting short_circuit_function_evaluation_for_nulls is enabled."}]}]} />

Ratio threshold of NULL values to execute functions with Nullable arguments only on rows with non-NULL values in all arguments. Applies when setting short\_circuit\_function\_evaluation\_for\_nulls is enabled.
When the ratio of rows containing NULL values to the total number of rows exceeds this threshold, these rows containing NULL values will not be evaluated.