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Scalar subquery cardinality ignores null-valued rows · case 04

Scalar subquery cardinality ignores null-valued rows.

Member previewVariant 4 · 3 implementations · 9 checks per implementation

Case contract

Evaluate a correlated scalar lookup per outer key. Zero rows yield None, exactly one row yields its value including None, and two or more matching rows yield the explicit value CARDINALITY. Count physical rows, not distinct or non-null values.

Why this case matters

A bounded deterministic data engine model makes representation and changelog faults reproducible.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
one null and one value	`[null]`	`["CARDINALITY"]`	Failed

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