Comparing FetchXML with OData in Power Automate: When to Use Each?

In Power Automate, when working with Dynamics 365 or the Microsoft Dataverse, two powerful query languages, FetchXML and OData, can be used to retrieve, filter, and manipulate data. Each has its own strengths, and understanding when to use FetchXML versus OData can make a significant difference in optimizing performance and achieving the desired results.

In this blog, we’ll compare FetchXML and OData, looking at their key differences, strengths, and specific use cases. This will help you decide which to use based on the requirements of your Power Automate flows.

1. What is FetchXML?

FetchXML is a proprietary query language used in Microsoft Dynamics 365 and Dataverse to retrieve data. It is an XML-based syntax and is highly versatile for querying CRM entities. It supports advanced filtering, aggregations, joins, and more.

Key Features:

• XML-based query language.
• Supports aggregations (SUM, COUNT, AVG, etc.).
• Allows for complex filtering and conditional logic.
• Fetches related entity records (joins).
• Offers flexibility in building intricate queries.

Example FetchXML Query:

<fetch top="10">
  <entity name="account">
    <attribute name="name" />
    <attribute name="accountid" />
    <filter>
      <condition attribute="statecode" operator="eq" value="0" />
    </filter>
  </entity>
</fetch>        

2. What is OData?

OData (Open Data Protocol) is a web standard protocol for querying and updating data. In Power Automate, OData is commonly used with the List Records action to query entities in the Dataverse. The syntax is URL-based and leverages standard query options like $filter, $select, and $orderby.

Key Features:

• URL-based querying language.
• Integrates seamlessly with APIs.
• Supports filtering, sorting, and paging.
• Simpler syntax for basic queries.
• Allows querying external data services that support OData.

Example OData Query:

accounts?$select=name,accountid&$filter=statecode eq 0&$top=10        

3. Key Differences Between FetchXML and OData

4. When to Use FetchXML in Power Automate

Use FetchXML when:

• Complex Queries: You need to perform complex data queries involving aggregations, nested filtering, or retrieving related entities (joins).
• Aggregations: Your flow requires sum, count, or other aggregate operations on datasets.
• Performance: You need to retrieve large amounts of data, and FetchXML's optimization for working with Dataverse data will offer better performance.
• Advanced Filtering: FetchXML offers more flexibility when it comes to complex filtering conditions.
• Reports and Dashboards: When building reports or exporting data to Power BI, FetchXML’s aggregations can simplify the process.

Example Use Case:

You're building a flow in Power Automate that needs to retrieve all accounts and their related contacts where the account’s annual revenue exceeds a certain threshold. FetchXML allows you to fetch these related records in a single query.

5. When to Use OData in Power Automate

Use OData when:

• Simple Queries: You need to fetch a limited number of fields and records without complex filtering or relationships.
• Performance: For small datasets, OData performs well, particularly if you're retrieving a few records at a time.
• External Integration: OData is widely used in external services, so if your flow integrates with an API or service that supports OData, it’s a natural fit.
• Simplicity: If you’re working with straightforward CRUD (Create, Read, Update, Delete) operations, OData’s URL-based syntax is easy to use.

Example Use Case:

You’re creating a flow to retrieve the top 5 open leads and send a daily email update to sales managers. OData is perfect for quickly querying this data without complexity.

6. Performance Considerations

• FetchXML is generally faster for larger datasets, complex filters, or when working directly with Dynamics 365 and Dataverse, as it’s optimized for these environments.
• OData, while simpler, might face limitations with larger datasets or complex queries. Pagination must be managed explicitly when querying large records.

Tip: If your query is performance-critical and involves significant data manipulation, FetchXML might be the better choice. For lightweight queries or external integrations, OData is more appropriate.

7. Combining FetchXML and OData in Power Automate

In some cases, you may need to combine the strengths of both. For example:

• Use OData for retrieving a small set of records for fast operations.
• Use FetchXML for more detailed or complex queries when performing advanced data manipulation.

You can even execute FetchXML queries via HTTP Requests if your flow integrates with external systems but needs FetchXML’s querying power.

Final Thoughts: When to Choose FetchXML or OData

• Choose FetchXML for complex, large-scale, or deeply filtered queries within the Dataverse and Dynamics 365. It’s especially suited for scenarios involving aggregations, joins, or nested filters.
• Choose OData for simple, URL-based queries or when integrating with external data sources or APIs that support the OData protocol.

By understanding the strengths of FetchXML and OData, you can design more efficient flows in Power Automate, balancing performance, simplicity, and functionality.