> ## 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.

# webassembly_udf_* session settings

> ClickHouse session settings in the webassembly_udf_* 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>;
};

export const ExperimentalBadge = () => {
  return <div className="experimentalBadge">
            <div className="experimentalIcon">
            <svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path strokeWidth="1.25" d="M5.5 2H10.5" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
                <path strokeWidth="1.25" d="M9.50015 2V6.19625L13.4283 12.7425C13.4738 12.8183 13.4985 12.9049 13.4996 12.9934C13.5008 13.0818 13.4785 13.169 13.435 13.246C13.3914 13.323 13.3283 13.3871 13.2519 13.4317C13.1755 13.4764 13.0886 13.4999 13.0002 13.5H3.00015C2.91164 13.5 2.8247 13.4766 2.74822 13.432C2.67174 13.3874 2.60847 13.3233 2.56487 13.2463C2.52126 13.1693 2.49889 13.082 2.50004 12.9935C2.50119 12.905 2.52582 12.8184 2.5714 12.7425L6.50015 6.19625V2" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
                <path strokeWidth="1.25" d="M4.47656 9.56754C5.30344 9.41254 6.47656 9.47942 7.99969 10.25C10.0153 11.2707 11.4216 11.0569 12.2184 10.7282" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
            </svg>
        </div>
            Experimental feature. <u><a href="/docs/docs/beta-and-experimental-features#experimental-features">Learn more.</a></u>
        </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="webassembly_udf_max_fuel">
  webassembly\_udf\_max\_fuel
</h2>

<ExperimentalBadge />

<SettingsInfoBlock type="UInt64" default_value="100000" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.3"},{"label": "100000"},{"label": "New setting to limit CPU instructions (fuel) per WebAssembly UDF instance execution."}]}]} />

Fuel limit per WebAssembly UDF instance execution. Each WebAssembly instruction consumes some amount of fuel. The value is scaled by 1024 before being passed to the runtime, so `webassembly_udf_max_fuel = 1` corresponds to approximately 1024 fuel units. Set to 0 for no finite limit. Applies only to functions whose per-function setting `webassembly_udf_enable_fuel` is true, which is the default.

<h2 id="webassembly_udf_max_input_block_size">
  webassembly\_udf\_max\_input\_block\_size
</h2>

<ExperimentalBadge />

<SettingsInfoBlock type="UInt64" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.3"},{"label": "0"},{"label": "New setting to limit input block size for WebAssembly UDFs."}]}]} />

Maximum number of rows passed to a WebAssembly UDF in a single block. Set to 0 to process all rows at once.

<h2 id="webassembly_udf_max_instances">
  webassembly\_udf\_max\_instances
</h2>

<ExperimentalBadge />

<SettingsInfoBlock type="UInt64" default_value="32" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.3"},{"label": "32"},{"label": "New setting to limit the number of parallel WebAssembly UDF instances per function."}]}]} />

Maximum number of WebAssembly UDF instances that can run in parallel per function.

<h2 id="webassembly_udf_max_memory">
  webassembly\_udf\_max\_memory
</h2>

<ExperimentalBadge />

<SettingsInfoBlock type="UInt64" default_value="134217728" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.3"},{"label": "134217728"},{"label": "New setting to limit memory per WebAssembly UDF instance."}]}]} />

Memory limit in bytes per WebAssembly UDF instance.