The footer already names every row-group byte range, so the adapter
only reads metadata: one extent per row group, the leading magic riding
with the first, and a trailing extent for the page indexes and footer.
Engines that fetch row groups by offset then read exactly the covering
chunks. Parquet needs no view; alignment alone delivers the benefit.
The ingest sidecar is an FFmpeg-style EXT-X-BYTERANGE media playlist;
its segments become the extents and 188 becomes the align quantum, so
every storage chunk holds whole TS packets of one segment. The view
renders a playback playlist with plain numbered segment URLs for
clients that do not speak byte-range HLS, and maps ?seq=N to the
segment's extent. Playlist state the generated playlist cannot
reproduce (EXT-X-KEY, MAP, DISCONTINUITY, GAP, I-frame-only) is
rejected at ingest.
A format adapter reduces one container format to three things the core
understands: extent sizes, an alignment quantum, and an opaque payload.
Capabilities beyond identity (Indexer, SidecarIndexer, Viewer) are
discovered by type assertion. The layout persists in one compact
extended attribute keyed by extent sizes rather than chunk ids, so it
survives chunk manifest folding, and the Cutter turns it into upload
chunk boundaries clamped by maxMB and the align quantum. The formattest
kit holds every adapter to no-panic parsing of truncated input.
Chris Lu