What is a manifest list?

A manifest list is an Avro file, one per snapshot, containing one record per manifest file belonging to that snapshot, along with a summary of each manifest's own partition-level bounds — effectively an index one level above the manifest files themselves.

This summary is what enables manifest-level pruning: a query engine can read just the manifest list (a comparatively small file) and, using its per-manifest partition bound summaries, immediately rule out entire manifests that can't possibly contain data matching the query — without ever opening those excluded manifests to inspect their individual data file entries.

This two-level pruning structure (manifest list pruning, then manifest pruning within the surviving manifests) is a big part of why Iceberg can maintain fast query planning even on tables with millions of files: rather than the query planner needing to inspect every single file's metadata individually, most of the search space is eliminated hierarchically, layer by layer, using progressively more granular summary statistics.