BigData / Apache Hudi Interview Questions
What is the difference between a global index and a partition-level index?
A partition-level (local) index assumes the record's partition path is already known and only checks files within that specific partition for a key match — fast, but it breaks if a record's partition value can change between updates.
| Partition-level index | Global index |
| Only scans files within the given partition. | Scans across all partitions in the table. |
| Faster; requires the correct partition to already be known. | Slower per lookup, but correct even if a record's partition changes. |
| Example: BLOOM, SIMPLE | Example: GLOBAL_BLOOM, GLOBAL_SIMPLE, RECORD_LEVEL_INDEX |
A global index enforces record-key uniqueness across the entire table rather than just within one partition, which matters when the same key could legitimately need to move partitions over time.
A global index enforces record-key uniqueness:
A partition-level index can break correctness when:
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