How can I optimize my n8n workflow for email parsing and Google Sheets upsertion?

Filter Data Before the Upsert:
Instead of relying solely on a code node to pick the right data, consider using n8n’s built-in nodes like Set or Function nodes only for what they do best. For many cases, simple conditional operations or filtering can be performed using node parameters.

Upsert Pattern:
The Google Sheets node supports operations like "Append or Update Row." You might refactor your code to use these built-in operations whenever possible to reduce complexity and potential errors.

• Use a Function node to iterate over the returned list from a single “Get Sheet” call.
• Cache or store the sheet list if it doesn’t change frequently, then reference it for subsequent checks.

• This not only makes your workflow easier to maintain but also provides a clear view of parameters that are used across multiple nodes.

• For example, one workflow could handle email parsing and data extraction, while another handles interaction with Google Sheets. This makes the logic easier to debug and maintain.

• You can route errors to a dedicated error handling branch in your workflow.

Limit Data Returned:
Instead of retrieving the entire spreadsheet data to check if a specific sheet exists, use a more focused query. For example, consider using the Google Sheets API’s A1 notation or the “Get Row(s)” operation with specified ranges so that you only retrieve what's necessary.

Use Built-in Operations:
Try leveraging the built-in operations that n8n provides (for example, the “Create” operation under “Sheet Within Document”) rather than relying on a custom code block. This can make it easier to manage and troubleshoot your workflow.

Append or Update Row Operation:
If you’re not already using it, consider utilizing the “Append or Update Row” operation. This built-in functionality may handle your scenario more robustly than a custom code block.

Reduce Custom Code:
When possible, try handling transformations with n8n’s native nodes (like Set or Function nodes for minor modifications) rather than writing extensive custom code. This improves maintainability and makes the logic more transparent.

Use Environment Variables or Credentials:
Instead of hardcoding constants directly within your workflow, consider storing these as environment variables or in n8n credentials (if they’re sensitive). This makes your workflow config more flexible and secure.

Centralize Configuration with a Dedicated Node:
Use a dedicated “Set” node early in your workflow to define constants. Then reference these variables throughout your flow using expressions. This centralizes configuration and makes it easier to update if needed.

Modularize Your Workflow:
If possible, break down the workflow into smaller, focused workflows (for example, one for sheet checking/creation and another for data upsertion). This can simplify debugging and improves clarity.

Performance Considerations:
When operating on large spreadsheets, limit your data queries with A1 notation, and use field masks (if using direct API calls) to only return the data that’s needed.