René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ScanIterator: nested struct column fails chunk planning (\"0 flats\" vs widest column)","articleBody":"Found by the Raincloud conformance PoC (#205). `countries-of-the-world` (written by `vortex-data==0.69.0`) has a top-level struct column `data` that is itself a struct — its layout subtree is `vortex.struct(262 rows) → 4× flat`. `ScanIterator.buildChunks` doesn't treat the nested struct layout as a chunk source and fails:\n\n```\nVortexException: scan: column 'data' has 0 flats but the widest column has 1;\nmixed per-column chunking beyond 1-vs-N is not supported\n    at ScanIterator.buildChunks(ScanIterator.java:144)\n```\n\nFull layout tree of the file:\n\n```\nstruct (262 rows)\n  region:       vortex.stats → 2× [vortex.dict → 2× flat]\n  country_code: vortex.stats → 2× flat\n  data:         vortex.struct(262 rows) → 4× flat\n```\n\n`schema`/`count`/`inspect` all handle the file; only the scan path fails. Repro: `python -m scripts.pipeline.build countries-of-the-world` in Raincloud, then `vortex-cli export countries-of-the-world.vortex`.","author":{"url":"https://github.com/dfa1","@type":"Person","name":"dfa1"},"datePublished":"2026-07-06T18:45:09.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/207/vortex-java/issues/207"}