FA-133 / Storage and queries / Member archive

A composite uniqueness check rejects SQL-valid nullable keys · case 03

Repeated tuples containing an unknown component are rejected as duplicate composite keys.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

Return whether a list of two-component keys satisfies ordinary NULL-distinct SQL UNIQUE semantics: two rows conflict only when both components in both rows are non-NULL and equal. None represents SQL NULL.

Why this case matters

Isolates a storage constraint's comparison contract. Some engines offer NULLS NOT DISTINCT constraints; that alternate contract is explicitly outside this experiment, so the model does not label it a database bug.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
unknown second component can repeat	`false`	`true`	Failed

MEMBER ARCHIVE

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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