AI / Apache Paimon Interview questions
What is the difference between Fixed Bucket and Dynamic Bucket modes?
Both decide which bucket a record lands in, but they solve different scaling problems:
| Mode | How buckets are assigned | Best for |
| Fixed Bucket | A fixed bucket count set with bucket = N; assignment is a deterministic hash of the bucket key. | Predictable data volume where you can size buckets up front; the fastest, simplest option. |
| Dynamic Bucket | bucket = -1; Paimon maintains an index mapping keys to buckets and grows bucket count automatically as data grows. | Unpredictable or growing key cardinality where a fixed count would need constant retuning. |
The tradeoff is that Dynamic Bucket needs to maintain that key-to-bucket index, which adds overhead and, in its simplest form, generally requires all data for a key to route through a single write task — making Fixed Bucket the better default whenever data volume is roughly known ahead of time.
Fixed Bucket mode is configured by setting bucket to:
Dynamic Bucket mode is best suited for:
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