BigData / Apache Hudi Interview Questions
What is Copy-on-Write (CoW) in Hudi?
In a Copy-on-Write table, every update is merged into the affected columnar (Parquet) file immediately at write time, producing a brand-new version of that file rather than editing it in place.
The result is a table made up entirely of plain Parquet files, so any engine that can read Parquet reads Hudi's latest state at native speed with no merge step at query time. The cost is on the write side — even a small update can trigger rewriting a whole Parquet file, which is why CoW suits read-heavy workloads with moderate update volume better than high-frequency streaming upserts.
In a CoW table, updates are merged into files:
CoW tables are best suited to:
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