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FA-45276 / Data systems / Open access

Column binding folds case in a case-sensitive schema · case 01

Column binding folds case in a case-sensitive schema.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

qualified-column-binding: Column binding folds case in a case-sensitive schema.

THE FAILURE

qualified-column-binding: Column binding folds case in a case-sensitive schema.

Unsuccessful approach: Whitespace trimming changes literal identifier identity too.

Case contract

Resolve query references [qualifier-or-None,name] against schema entries [relation,name,field-id]. Unqualified names bind only when exactly one matching column exists. Qualified names use both relation and name; no candidates yields MISSING and several yield AMBIGUOUS. Return stable field IDs.

Why this case matters

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

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(d):
    try:
        schema,references=d
        out=[]
        for qualifier,name in references:
            matches=[field for rel,col,field in schema if col.lower()==name.lower() and (qualifier is None or rel==qualifier)]
            if not matches: out.append('MISSING')
            elif len(matches)>1: out.append('AMBIGUOUS')
            else: out.append(matches[0])
        return out
    except (IndexError, KeyError, ValueError, StopIteration) as exc:
        return {"representation_error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('qualified same name', solve([[['a', 'x', 1], ['b', 'x', 2]], [['b', 'x'], ['a', 'x']]]), [2, 1])
    check('ambiguous', solve([[['a', 'x', 1], ['b', 'x', 2]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 1]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 1]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 1]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 1]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 1]], [['a', 'x'], ['a', 'x']]]), [1, 1])
elif N == 2:
    check('qualified same name', solve([[['a', 'x', 2], ['b', 'x', 3]], [['b', 'x'], ['a', 'x']]]), [3, 2])
    check('ambiguous', solve([[['a', 'x', 2], ['b', 'x', 3]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 2]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 2]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 2]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 2]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 2]], [['a', 'x'], ['a', 'x']]]), [2, 2])
elif N == 3:
    check('qualified same name', solve([[['a', 'x', 3], ['b', 'x', 4]], [['b', 'x'], ['a', 'x']]]), [4, 3])
    check('ambiguous', solve([[['a', 'x', 3], ['b', 'x', 4]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 3]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 3]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 3]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 3]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 3]], [['a', 'x'], ['a', 'x']]]), [3, 3])
elif N == 4:
    check('qualified same name', solve([[['a', 'x', 4], ['b', 'x', 5]], [['b', 'x'], ['a', 'x']]]), [5, 4])
    check('ambiguous', solve([[['a', 'x', 4], ['b', 'x', 5]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 4]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 4]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 4]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 4]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 4]], [['a', 'x'], ['a', 'x']]]), [4, 4])
elif N == 5:
    check('qualified same name', solve([[['a', 'x', 5], ['b', 'x', 6]], [['b', 'x'], ['a', 'x']]]), [6, 5])
    check('ambiguous', solve([[['a', 'x', 5], ['b', 'x', 6]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 5]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 5]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 5]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 5]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 5]], [['a', 'x'], ['a', 'x']]]), [5, 5])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
qualified same name[2, 1][2, 1]Passed
ambiguous['AMBIGUOUS']['AMBIGUOUS']Passed
missing['MISSING']['MISSING']Passed
case-sensitive[1]['MISSING']Failed
alias-prefix['MISSING']['MISSING']Passed
literal-space['MISSING']['MISSING']Passed
repeat ref[1, 1][1, 1]Passed

SHA-256 / 91b04dc165e1c3aa604b5e6199da2e3f803748379f55f97e14a3893a90eef84a

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(d):
    try:
        schema,references=d
        out=[]
        for qualifier,name in references:
            matches=[field for rel,col,field in schema if col.strip()==name.strip() and (qualifier is None or rel==qualifier)]
            if not matches: out.append('MISSING')
            elif len(matches)>1: out.append('AMBIGUOUS')
            else: out.append(matches[0])
        return out
    except (IndexError, KeyError, ValueError, StopIteration) as exc:
        return {"representation_error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('qualified same name', solve([[['a', 'x', 1], ['b', 'x', 2]], [['b', 'x'], ['a', 'x']]]), [2, 1])
    check('ambiguous', solve([[['a', 'x', 1], ['b', 'x', 2]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 1]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 1]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 1]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 1]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 1]], [['a', 'x'], ['a', 'x']]]), [1, 1])
elif N == 2:
    check('qualified same name', solve([[['a', 'x', 2], ['b', 'x', 3]], [['b', 'x'], ['a', 'x']]]), [3, 2])
    check('ambiguous', solve([[['a', 'x', 2], ['b', 'x', 3]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 2]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 2]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 2]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 2]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 2]], [['a', 'x'], ['a', 'x']]]), [2, 2])
elif N == 3:
    check('qualified same name', solve([[['a', 'x', 3], ['b', 'x', 4]], [['b', 'x'], ['a', 'x']]]), [4, 3])
    check('ambiguous', solve([[['a', 'x', 3], ['b', 'x', 4]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 3]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 3]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 3]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 3]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 3]], [['a', 'x'], ['a', 'x']]]), [3, 3])
elif N == 4:
    check('qualified same name', solve([[['a', 'x', 4], ['b', 'x', 5]], [['b', 'x'], ['a', 'x']]]), [5, 4])
    check('ambiguous', solve([[['a', 'x', 4], ['b', 'x', 5]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 4]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 4]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 4]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 4]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 4]], [['a', 'x'], ['a', 'x']]]), [4, 4])
elif N == 5:
    check('qualified same name', solve([[['a', 'x', 5], ['b', 'x', 6]], [['b', 'x'], ['a', 'x']]]), [6, 5])
    check('ambiguous', solve([[['a', 'x', 5], ['b', 'x', 6]], [[None, 'x']]]), ['AMBIGUOUS'])
    check('missing', solve([[['a', 'x', 5]], [['a', 'z']]]), ['MISSING'])
    check('case-sensitive', solve([[['a', 'X', 5]], [[None, 'x']]]), ['MISSING'])
    check('alias-prefix', solve([[['ab', 'x', 5]], [['a', 'x']]]), ['MISSING'])
    check('literal-space', solve([[['a', ' x ', 5]], [[None, 'x']]]), ['MISSING'])
    check('repeat ref', solve([[['a', 'x', 5]], [['a', 'x'], ['a', 'x']]]), [5, 5])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
qualified same name[2, 1][2, 1]Passed
ambiguous['AMBIGUOUS']['AMBIGUOUS']Passed
missing['MISSING']['MISSING']Passed
case-sensitive['MISSING']['MISSING']Passed
alias-prefix['MISSING']['MISSING']Passed
literal-space[1]['MISSING']Failed
repeat ref[1, 1][1, 1]Passed

SHA-256 / e5c4f37362d982c89f53f9030a17190639ad83d3c1534453793681356a1457a8

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

Offline stipulated semantics over valid small inputs; no performance, concurrency, or production-engine conformance claim. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:44:20.795537+00:00.

Case digest / c4ff44f5521fdd64fd0b560833b8b1fc293202934c17404e7106397f9fef508f