> ## 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.

# allow_nondeterministic_* session settings

> ClickHouse session settings in the allow_nondeterministic_* 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="allow_nondeterministic_mutations">
  allow\_nondeterministic\_mutations
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

User-level setting that allows mutations on replicated tables to make use of non-deterministic functions such as `dictGet`.

Given that, for example, dictionaries, can be out of sync across nodes, mutations that pull values from them are disallowed on replicated tables by default. Enabling this setting allows this behavior, making it the user's responsibility to ensure that the data used is in sync across all nodes.

**Example**

```xml theme={null}
<profiles>
    <default>
        <allow_nondeterministic_mutations>1</allow_nondeterministic_mutations>

        <!-- ... -->
    </default>

    <!-- ... -->

</profiles>
```

<h2 id="allow_nondeterministic_optimize_skip_unused_shards">
  allow\_nondeterministic\_optimize\_skip\_unused\_shards
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

Allow nondeterministic (like `rand` or `dictGet`, since later has some caveats with updates) functions in sharding key.

Possible values:

* 0 — Disallowed.
* 1 — Allowed.