AI / Apache Paimon Interview questions
List the merge engines Paimon supports for primary key tables?
When Paimon receives two or more records sharing a primary key, the table's merge-engine property decides how they're combined into one:
| Merge engine | Behavior |
| Deduplicate (default) | Keeps only the latest record; discards the rest. |
| Partial Update | Merges non-null fields from multiple records column by column. |
| Aggregation | Applies a per-field aggregate function (sum, max, etc.) across records. |
| First Row | Keeps the first record seen for a key and ignores subsequent ones. |
Which one to pick depends entirely on what "merging two records" should mean for your data: a plain upsert wants Deduplicate, a wide dimension table assembled from multiple sources wants Partial Update, a running counter wants Aggregation.
Which merge engine keeps only the latest record for a duplicate primary key?
Which merge engine merges non-null field values from multiple records?
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