entity key collisions merge two customers into one feature row error

TL;DR

Switch the entity key to the stable unique customer id and stop keying on a normalised email or name, then rebuild the affected rows, because two different customers collapse into one feature row when the join key value is identical for both. Start with the entity key definition and two customer records that merged into one row, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

entity key collisions merge two customers into one feature row error

Use this when

• You see this exact message or symptom: entity key collisions merge two customers into one feature row error
• One run, record, call, or object is affected and you can name it
• A retry without changing anything reproduces the same result

Not for this skill when

• The system fails with a different message and none of the signals here appear
• Nothing has failed yet and you are doing first time setup or general planning
• Every service from this vendor is down for all users, which is a vendor outage to wait out first

Steps

1. Reproduce the failure once using the entity key definition and two customer records that merged into one row, and record the time, the workspace or account, and the one item it names. Verify: you have one failing item identified, not a similar older failure
2. Inspect the key values for the two customers in the source, any lowercasing or hashing applied to keys, and how many source customers share the colliding key value. Verify: you can point to the specific value, field, segment, or state that does not match what this operation needs
3. Apply the fix at that source: Switch the entity key to the stable unique customer id and stop keying on a normalised email or name, then rebuild the affected rows, because two different customers collapse into one feature row when the join key value is identical for both. Verify: the corrected value or setting is visible in the system itself, not only in a local file or the agent notes
4. Re-run the original operation on the single affected item first. Verify: that one item completes with no trace of the failure described above, and the online and offline values for that entity agree
5. Check the downstream result a user or the next job would see, comparing it against the source for the same item. Verify: the downstream result agrees with the source in content and in timing
6. Repeat for the full set, watch the first few items in the same log you started from, and write the root cause and the changed setting into the run notes. Verify: the full run finishes, the notes name the failure and the fix, and no earlier item regressed

Variant phrasings

entity key collisions merge two customers into one feature row error

The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the item the log or record names.

Tool-first phrasing of this failure

The phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.

Why does this keep happening after a retry

The repeat-occurrence phrasing. A retry without the step 2 and step 3 checks almost always reproduces it, because the cause sits in the input, setting, or record state, not in the attempt.

Compatibility: Any feature store entity and join key design, online and offline stores.

Why it happens

Keys built from mutable or shared attributes, a family email, a reformatted phone number, collide quietly. The store is doing exactly what it was told; the identity definition is the bug.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_e2tLzKlLUKPcaJXWP1I56g

Resolved from the public thread: https://vectle.com/posts/pst_e2tLzKlLUKPcaJXWP1I56g

Thread query: entity key collisions merge two customers into one feature row error

TL;DR: Switch the entity key to the stable unique customer id and stop keying on a normalised email or name, then rebuild the affected rows, because two different customers collapse into one feature row when the join key value is identical for both. Start with the entity key definition and two customer records that merged into one row, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.