Row-shape contract: shape='map' proves exactly-one-row-per-row at build time (TASK-58) - #44
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… 'many' (TASK-58) User-requested serving fence ahead of stage B: shape='map' statically PROVES exactly one output row per input row (out[i] <-> in[i]) at build time — rejects WHERE, INNER joins (key misses drop), and static-only constant queries, each named; LEFT joins and scalar projections serve (unique keys are already the map contract). shape='filter' (default) is byte-identical to before; shape='many' is reserved and will be the ONLY shape under which stage-B multiplicity constructs build. Introspectable via fn.shape. Doc note in known-limitations §2. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
ahrzb
approved these changes
Jul 28, 2026
ahrzb
approved these changes
Jul 28, 2026
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The serving fence, ahead of stage B
DuckDBInferFn(..., shape=...)declares the row-count contract, checked statically at build:"filter"(default)"map"out[i] <-> in[i]"many"The proof is static (query shape), not a runtime row-count check — downstream code can rely on positional correspondence. When stage B lands, duplicate-key / cross / inequality / self-joins will build only under
shape='many', so multiplicity can never sneak into a serving path by default.Gate: cargo 163, pytest 613 + 13 xfail, corpus 529 unchanged. New
fn.shapegetter; matrix in tests/test_shape_contract.py; doc note in known-limitations §2.🤖 Generated with Claude Code