BigData / Apache Hudi Interview Questions
How do you troubleshoot slow upserts in a Hudi table?
Slow upserts almost always trace back to one of a few common culprits, so it's worth checking them in order.
- Check the index type — a Bloom or Simple index scanning many files under heavy random-update patterns is far slower than a Record-Level Index at scale.
- Look for small-file sprawl — more files means more index lookups and more merge work per batch.
- Check whether the Metadata Table is enabled — without it, every operation may be paying the cost of listing files directly against cloud storage.
- Review partition/key design — a poor HoodieKey choice can create hot partitions or force expensive global index scans.
- Check table-service backlog — a MoR table with compaction falling behind means every upsert also merges against a growing pile of log files.
Under heavy random-update patterns at scale, which index tends to be faster?
A falling-behind compaction backlog on a MoR table causes upserts to:
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