> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://help.sigmacomputing.com/docs/configure-data-loading/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://help.sigmacomputing.com/_mcp/server.

# Configure data loading

> Optimize performance of documents in Sigma by configuring when an element uses the browser cache to load data from your data platform.

Sigma uses queries to retrieve data from your connected data platform. To optimize performance and reduce the number of queries sent to your data platform, the browser cache is used. You can configure when an element uses the browser cache with Alpha Query to help accelerate the performance of some workbook elements.

To determine the best way to optimize performance for your workbook, see [Best practices for improved document performance](/docs/best-practices-for-improved-performance).

## User requirements

You must have the **Create, edit, and publish workbooks** permission enabled on your account type and **Can edit** access to the workbook.

## Configure data loading

To accelerate performance of your workbook, configure data loading for one or more elements in a workbook. Elements that benefit from configuring data loading include parent elements with multiple child elements, and elements referenced by other elements, such as with a lookup.

To configure data loading:

1. Open a workbook for editing.

2. Open the workbook lineage to identify the optimal parent elements on which to configure this setting. Elements with multiple child elements are good candidates to configure data loading.

   ![Workbook lineage with a parent element, CENSUS that is a table with 13 child elements dependent on it, 12 KPI elements and 1 Donut chart.](/_fern-img/b9dc428154f75eb758bf1ab3c044c383f46814172177aeebba7221ff5f81a3db.webp)

3. For each relevant parent element, click **View element** to open the workbook canvas with the element selected.

   ![Workbook lineage with the Census table parent element selected and showing view element on the details card, which also shows that the table is sourced from the Corporate Database connection.](/_fern-img/2dfd38987246ef944e6c3cdcc3fb5820b54e9aacd21039996eb9c8ba730b0643.webp)

4. On the element toolbar, select ![](https://sigma-docs-screenshots.s3.us-west-2.amazonaws.com/Icons/more.svg) **More**, then select **Advanced options** > **Configure data loading...**.

   The **Configure data loading** popover appears.

   ![Configure data loading popover, showing a dropdown menu to choose the Alpha Query prefetch mode, and a diagnostics section with a source row count and the output row count.](/_fern-img/fa53f3dbb342068419668c117e405d01351af646ceca531eae5443339ca43de2.webp)

5. Review the **Diagnostics** section to validate that the query results for the element are likely to be prefetched:

   * The **Source row count** is at least 1. Alpha Query attempts to prefetch the entire data table to cache it in the browser cache, so smaller result sets are more likely to be prefetched. Wide tables or elements with JSON columns more quickly reach the browser cache limit, and instead might only have 10,000 rows of data cached.
   * The **Source row count** and the **Output row count** match.

6. For **Alpha Query prefetch mode**, select **Always**.

   Your changes are automatically applied to the draft of the workbook.

   Data loading for an element has 3 possible modes:

   | Alpha Query prefetch mode | Effect                                                                                                                                                                                                                                                                                    |
   | ------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
   | **Default**               | Sigma uses statistics and history to automatically decide when to prefetch data.                                                                                                                                                                                                          |
   | **Always**                | Sigma always prefetches data for this element to be used by other data elements in the document. If data is in the browser cache and can be used, Sigma uses that data. If data is not in the browser cache, Sigma runs a query against the connected data platform to retrieve the data. |
   | **Never**                 | Sigma never prefetches data for this element. Run a query against the connected data platform every time.                                                                                                                                                                                 |

7. Publish the workbook for your changes to take effect on the published version.

8. (Optional) Review the [query history for the workbook](/docs/examine-workbook-queries) to confirm that the selected element is the only element that is retrieving data from the warehouse when the workbook is first loaded, and subsequent actions rely on browser calculations.

   ![Query history for the workbook, showing a warehouse query for the parent CENSUS element and browser calculations for other relevant data](/_fern-img/d673f76009cadb1053cf8a15a32415ff38fd312ac8c0e15af4b8be67432055a3.webp)

## What happens when data loading is set to **Always**

When you have multiple elements in your document that use or reference the same data element, like as a data source or for a lookup, Sigma performs a "prefetch query" to retrieve the data for the referenced data element and store it in the web browser cache. Normally, the parent element must load within the 8-second prefetch timeout. If the parent element takes longer to load, the prefetch query is cancelled and instead separate queries are run for each child element.

For example, if you have 10 charts that use a table in your document as a data source, Sigma runs one prefetch query to retrieve the data for the parent table, rather than running 11 individual queries to retrieve the data for each of the data elements.

After that prefetch query is performed, Alpha Query can process the data, performing calculations with the cached data instead of querying the data warehouse for every element.

If you configure data loading to **Always** on a parent element, Sigma always runs the prefetch query. If the prefetch query does not complete before the 8-second prefetch timeout, Sigma waits until the connection timeout for the query is reached before cancelling the prefetch query. After the prefetch query completes, the child elements use the cached data:

```mermaid
flowchart TD
    A[Parent element with Alpha Query set to **Always**]
    A -->|uses cached data| B[Child]
    A -->|uses cached data| C[Child]
    A -->|uses cached data| D[Child]

style A fill:#4CEC8C
style B fill:#FF9A74
style C fill:#FF9A74
style D fill:#FF9A74
```

## Related resources

* [Caching and data freshness](/docs/caching-and-data-freshness)
* [Examine workbook and data model queries](/docs/examine-workbook-queries)
* [Best practices for improved document performance](/docs/best-practices-for-improved-performance)

> Official documentation and guidance for using Sigma to build AI apps, dashboards, and agents on governed warehouse data.