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

# Merge Async Results Stage

export const schema = {
  "type": "object",
  "title": "Merge Async Results",
  "description": "Wait for previous asynchronous stages to complete and merge their results into the active request",
  "required": ["timeoutMs", "asyncStageIds", "strictAsyncIds", "failFast"],
  "properties": {
    "skip": {
      "type": "boolean",
      "title": "Skip This Stage",
      "description": "Set to true to skip this stage.",
      "default": false,
      "hints": ["advanced"]
    },
    "label": {
      "type": "string",
      "title": "Label",
      "description": "A unique label for this stage.",
      "hints": ["advanced"],
      "maxLength": 255
    },
    "condition": {
      "type": "string",
      "title": "Condition",
      "description": "Define a conditional script that must result in true or false. This can be used to determine if the stage should process or not.",
      "hints": ["code", "code/javascript", "advanced"]
    },
    "legacy": {
      "type": "boolean",
      "title": "Legacy",
      "description": "True if this stage only supports legacy mode",
      "hints": ["readonly", "hidden"]
    },
    "timeoutMs": {
      "type": "integer",
      "title": "Timeout",
      "description": "Maximum amount of time (in milliseconds) that this stage will wait for completion of the configured asynchronous stages. If this timeout is reached and not all asynchronous stages have completed, it will abort the unfinished ones",
      "default": 1000,
      "minimum": 1,
      "exclusiveMinimum": false
    },
    "asyncStageIds": {
      "type": "array",
      "title": "Async IDs",
      "items": {
        "type": "string"
      }
    },
    "strictAsyncIds": {
      "type": "boolean",
      "title": "Strict Async IDs",
      "description": "Throw an error if one of the reference Async IDs is missing from the context.",
      "default": true
    },
    "failFast": {
      "type": "boolean",
      "title": "Fail Fast",
      "description": "Sets the fail-fast behavior. If selected, will abort any asynchronous calls we are waiting for after the first failure.",
      "default": false
    }
  },
  "category": "Fetch Data",
  "categoryPriority": 6,
  "unsafe": false
};

export const SchemaParamFields = ({schema}) => {
  const sanitize = str => {
    if (typeof str !== "string") return str;
    return str.replace(/^"(.*)"$/s, "$1").replace(/\\/g, "").replace(/"/g, "'");
  };
  const formatDescription = str => {
    const s = sanitize(str);
    return (/[.!?]\)*$/).test(s) ? s : `${s}.`;
  };
  const {description, properties = {}, required: requiredProps = []} = schema;
  const visibleProps = useMemo(() => Object.entries(properties).filter(([, prop]) => !prop.hints?.includes("hidden")), [properties]);
  return <div>
      {description && <p>{formatDescription(description)}</p>}

      {visibleProps.map(([name, prop]) => {
    const isRequired = requiredProps.includes(name);
    const hasDefault = prop.default !== undefined;
    const rawDefault = prop.default;
    const isComplexDefault = hasDefault && (typeof rawDefault === "object" || typeof rawDefault === "string" && (rawDefault.length > 20 || rawDefault.includes('"')));
    const fieldProps = {
      key: name,
      body: prop.title || name,
      type: prop.type,
      ...prop.title && ({
        post: [<><span className="text-stone-400 dark:text-stone-500">API property: </span>{name}</>]
      }),
      ...isRequired && ({
        required: true
      }),
      ...!isComplexDefault && hasDefault ? {
        default: sanitize(String(rawDefault))
      } : {}
    };
    const isObject = prop.type === "object" && prop.properties;
    const isArrayOfObjects = prop.type === "array" && prop.items?.type === "object" && prop.items.properties;
    return <ParamField {...fieldProps}>
            {prop.description && <p>{formatDescription(prop.description)}</p>}

            {isComplexDefault && <div className="flex">
                <p>
                  <strong>Default:</strong>
                </p>
                <pre className="!my-0">
                  <code>
                    {JSON.stringify(rawDefault, null, 2)}
                  </code>
                </pre>
              </div>}

            {isArrayOfObjects && <div className="flex">
              <p>
                <strong>Object attributes:</strong>
              </p>
              <pre className="!my-0">
                <code>
                  {'{\n'}
                  {Object.entries(prop.items.properties).map(([iname, iprop]) => <>
                      {`  ${iname}`}
                      {prop.items?.required?.includes(iname) && <span style={{
      color: 'red'
    }}> required</span>}
                      {`: {\n    display name: ${sanitize(iprop.title || '')}\n    type: ${iprop.type}\n  }\n`}
                    </>)}
                  {'}'}
                </code>
              </pre>
              </div>}

            {isObject && <Expandable title="properties">
                <SchemaParamFields schema={{
      properties: prop.properties,
      required: prop.required
    }} />
              </Expandable>}
          </ParamField>;
  })}
    </div>;
};

export const LwTemplate = ({title = "Key questions to get you started", icon = "sparkles", cta = "Powered by Agent Studio", linkHref = "https://lucidworks.com/demo/?utm_source=docs&utm_medium=referral&utm_campaign=docs_cta_ai"}) => {
  const [isLoaded, setIsLoaded] = useState(false);
  useEffect(() => {
    const timer = setTimeout(() => {
      setIsLoaded(true);
    }, 500);
    return () => clearTimeout(timer);
  }, []);
  return <div className="lw-template-container">
      <Card title={title} icon={icon}>
        {isLoaded && <span dangerouslySetInnerHTML={{
    __html: `<lw-template id="a029c1a9-28be-427e-b0e1-5d918920246a"></lw-template
            >`
  }} />}
        <Link href={linkHref} className="agent-studio-link text-left text-gray-600 gap-2 dark:text-gray-400 text-sm font-medium flex flex-row items-center hover:text-primary dark:hover:text-primary-light group-hover:text-primary group-hover:dark:text-primary-light">Powered by Lucidworks Agent Studio</Link>
      </Card>
    </div>;
};

[localhost link]: http://localhost:3000/docs/5/fusion/reference/config-ref/pipeline-stages/query-stages/merge-async-results-query-stage

[mintlify link]: https://doc.lucidworks.com/docs/5/fusion/reference/config-ref/pipeline-stages/query-stages/merge-async-results-query-stage

[old doc.lw link]: https://doc.lucidworks.com/fusion/5.9/266

Wait for previous [asynchronous stages](/docs/5/fusion/getting-data-out/query-basics/query-pipelines/overview) to complete and merge their results into the active request.

<LwTemplate />

## Query pipeline stage condition examples

Stages can be triggered conditionally when a script in the **Condition** field evaluates to true.
Some examples are shown below.

Run this stage only for mobile clients:

```js wrap  theme={"dark"}
params.deviceType === "mobile"
```

Run this stage when debugging is enabled:

```js wrap  theme={"dark"}
params.debug === "true"
```

Run this stage when the query includes a specific term:

```js wrap  theme={"dark"}
params.q && params.q.includes("sale")
```

Run this stage when multiple conditions are met:

```js wrap  theme={"dark"}
request.hasParam("fusion-user-name") && request.getFirstParam("fusion-user-name").equals("SuperUser");
!request.hasParam("isFusionPluginQuery")
```

The first condition checks that the request parameter "fusion-user-name" is present and has the value "SuperUser".
The second condition checks that the request parameter "isFusionPluginQuery" is not present.

## Configuration

<Tip>
  When entering configuration values in the UI, use *unescaped* characters, such as `\t` for the tab character. When entering configuration values in the API, use *escaped* characters, such as `\\t` for the tab character.
</Tip>

<SchemaParamFields schema={schema} />