BigData / Apache Iceberg Interview questions
What file formats does Iceberg use to store data?
Iceberg's data files — the actual rows and columns of table data — are most commonly stored as Parquet, though Iceberg also supports ORC and Avro as alternative underlying file formats, since the table format specification is deliberately decoupled from any single physical file format.
| Format | Typical Fit |
| Parquet | The most common choice; columnar, efficient for analytical scans |
| ORC | Another columnar option, historically common in Hive-based environments |
| Avro | Row-oriented; used internally by Iceberg itself for manifests, less common for primary data storage |
Parquet is the default and by far the most widely used choice in practice, largely because its columnar layout and rich per-column statistics align well with the same kind of predicate pushdown and column pruning that Iceberg's own manifest-level statistics are designed to support at a higher level.
Because the file format choice is a table-level (or even file-level) configuration detail rather than something baked permanently into the table format's design, an Iceberg table could in principle mix file formats across different data files, though in practice most tables consistently use one format for simplicity and predictable performance characteristics.
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