BigData / Apache Hudi Interview Questions
How does the Column Stats index differ from the Bloom filter index?
The Bloom filter index is built to answer point-lookup questions during upserts — "does this specific record key exist in this file?" — and lives in the Metadata Table's bloom filter partition.
The Column Stats index serves a different purpose: it stores per-file min/max (and other) statistics for arbitrary columns, not just the record key, so a query engine's planner can prune entire files out of a scan based on a WHERE predicate — the same idea as Parquet's own footer statistics, but centralized in the Metadata Table for faster access across many files. In short, Bloom filters accelerate write-time upserts, while Column Stats accelerate read-time query planning.
The Bloom filter index is primarily used during:
The Column Stats index mainly helps with:
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