Merge Multi-Execution Dedup by Key with Count Reconciliation Report

How it works

1. 1.Manual Trigger starts two Code nodes emitting fictional branch A and B samples with overlapping keys and invalid keyless records
2. 2.Merge in append mode with two inputs: each branch wired to its own input index
3. 3.A runOnceForAllItems Code node validates key type (string/number), trims it, counts invalid keyless records, and dedups keeping the variant with the most non-empty fields
4. 4.It computes unique keys per input, their union, per-key occurrence counts, and compares output unique keys to the union (counts_match)
5. 5.If routes match to the OK NoOp and deviation to the alert NoOp; both meet in a final Code node producing exactly one report item
6. 6.A final Set stamps the report title with includeOtherFields preserving all fields

Use cases

• Removing duplicate records after merging two simultaneously active branches in n8n
• Locally verifying merge input counts match output counts
• Diagnosing partial merge results that emit rows from only one input
• Producing a reconciliation report before handing data to any downstream system

Requirements

• n8n 2.44.6 with Code, Set, If, Merge, NoOp and StickyNote nodes
• Two same-schema JSON inputs containing record_key and __source to identify the branch (replace the two sample emitters with your real sources)
• No credentials and no external calls required

Setup and testing in n8n

1. Import the JSON into n8n and open the workflow
2. Execute the Manual Trigger and inspect Stamp Report Title output: 9 items received, 4 unique, counts_match true, ORD-1001 (3x) and ORD-1002 (2x) duplicated, 2 invalid records
3. Verify ORD-1002 was kept from branch B (5 fields) and ORD-1001 from branch A (6 non-empty fields)
4. Edge case: empty both sample arrays in the branch nodes and confirm status=no_input
5. To test the deviation path, manually paste the dedup output twice into the Merge inputs and watch If route to the alert path

Service Value

Ready-made workflow template for automation delivery and service execution.