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The Union node stacks rows from two data streams vertically into a single output - like appending one spreadsheet below another. Unlike Merge (which joins data side-by-side), Union appends data vertically. It can optionally deduplicate records based on mapped fields.

Basic Example

Input 1 Input 2 Result (Union)

How it works

1

Connect two inputs

Drag two data streams into the Union node. These can come from any upstream nodes in your workflow.
2

Choose a union type

Select how the rows from both inputs should be combined.
3

Configure dedup settings (optional)

When using Distinct mode, configure which fields define uniqueness and which input wins on duplicates.Dedup Key - select which fields from each input correspond to each other. These field pairs define uniqueness for deduplication. You can add multiple fields for a composite key (e.g., ID + Date).Priority - when duplicates are found, controls which input’s row is kept.
Field mappings are required when using Distinct mode. In All mode they are optional - rows are simply stacked.

Output

The Union node produces a single output stream containing the combined rows from both inputs. The output is available as an input to any downstream node in your workflow.

Example with Deduplication

Input 1 Input 2 Configuration: Distinct, Dedup Key: ID, Priority: Input 1 wins Result:

All vs Distinct

When using All, if both tables contain the same record, the result will include it twice: When using Distinct, duplicates are removed based on the dedup key, keeping only one row per unique combination.

Union vs Merge vs Bond

Best Practices

  • Ensure inputs have compatible schemas (same fields and meaning)
  • Use All when you want full data coverage and duplicates are acceptable
  • Use Distinct when you need a clean dataset and duplicate records must be removed
  • Carefully define dedup keys and priority rules

Common Pitfalls

  • Mismatched columns - same name but different meaning across inputs
  • Missing dedup key - leads to incorrect duplicate removal
  • Over-aggressive deduplication - can cause data loss
  • Merge Node - joins two datasets side-by-side rather than stacking vertically
  • Bond Node - creates logical relationships between entities