BigData / Apache Hudi Interview Questions
How does the Bloom index work in Hudi?
The Bloom index stores a bloom filter — a probabilistic, space-efficient data structure — along with min/max record-key range stats for each data file, historically in the file's footer and now more efficiently in the Metadata Table's dedicated bloom filter partition.
To tag an incoming record, Hudi first uses the min/max range to skip files that can't possibly contain the key, then checks the bloom filter for the remaining candidates. A bloom filter can have false positives (saying "maybe present" when it isn't) but never false negatives, so any positive match is verified by an actual key lookup. This range-pruning plus probabilistic filtering is what keeps Bloom index lookups fast without needing a full scan.
A bloom filter's possible outputs are:
Before checking the bloom filter itself, Hudi first uses:
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