What is a manifest file?

A manifest file is an Avro file that lists the actual data files belonging to a specific portion of a snapshot, with one record per data file, including that file's physical path, format, and per-column statistics like value counts, null counts, and min/max bounds.

Because a manifest carries min/max bounds for every column of every data file it references, a query engine can use those bounds to skip reading an entire data file outright if the file's statistics prove it can't possibly contain any rows matching the query's filter — a form of file-level pruning that happens before any actual data reading occurs, purely from metadata.

Iceberg reuses unchanged manifest files across snapshots wherever possible — if a write only touches a specific partition, manifests describing untouched partitions don't need to be rewritten — which keeps the metadata overhead of frequent small commits manageable rather than requiring a full metadata rewrite on every single write.