FA-44476 / Data systems / Open access
A struct field exposes values beneath null field lanes · case 01
A struct field exposes values beneath null field lanes.
ROOT CAUSE
struct-vector-project: A struct field exposes values beneath null field lanes.
VERIFIED REPAIR
Preserve the stated physical representation and operation order: Project requested fields from a struct array. Parent validity dominates field validity, absent schema fields materialize None, selection retains row order, and projection retains requested field order.
Unsuccessful approach: Whole-column validity nulls unrelated valid rows.
Case contract
Project requested fields from a struct array. Parent validity dominates field validity, absent schema fields materialize None, selection retains row order, and projection retains requested field order.
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:
columns,valid,parent,selection,fields=d
out=[]
for row in selection:
record=[]
for field in fields:
present=field in columns
known=present
value=columns[field][row] if present else None
record.append(value if parent[row] and known else None)
out.append(record)
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('gather with field order', solve([{'a': [1, 2], 'b': [3, 4]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[4, 2], [3, 1]])
check('parent hides values', solve([{'a': [1, 2]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [2]])
check('field null lane', solve([{'a': [1, 2]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [2]])
check('missing field', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[1, None]])
check('repeated projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[1, 1]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 2:
check('gather with field order', solve([{'a': [2, 3], 'b': [4, 5]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[5, 3], [4, 2]])
check('parent hides values', solve([{'a': [2, 3]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [3]])
check('field null lane', solve([{'a': [2, 3]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [3]])
check('missing field', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[2, None]])
check('repeated projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[2, 2]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 3:
check('gather with field order', solve([{'a': [3, 4], 'b': [5, 6]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[6, 4], [5, 3]])
check('parent hides values', solve([{'a': [3, 4]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [4]])
check('field null lane', solve([{'a': [3, 4]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [4]])
check('missing field', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[3, None]])
check('repeated projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[3, 3]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 4:
check('gather with field order', solve([{'a': [4, 5], 'b': [6, 7]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[7, 5], [6, 4]])
check('parent hides values', solve([{'a': [4, 5]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [5]])
check('field null lane', solve([{'a': [4, 5]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [5]])
check('missing field', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[4, None]])
check('repeated projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[4, 4]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 5:
check('gather with field order', solve([{'a': [5, 6], 'b': [7, 8]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[8, 6], [7, 5]])
check('parent hides values', solve([{'a': [5, 6]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [6]])
check('field null lane', solve([{'a': [5, 6]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [6]])
check('missing field', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[5, None]])
check('repeated projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[5, 5]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], []]), [[]])
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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| gather with field order | [[4, 2], [3, 1]] | [[4, 2], [3, 1]] | Passed |
| parent hides values | [[None], [2]] | [[None], [2]] | Passed |
| field null lane | [[1], [2]] | [[None], [2]] | Failed |
| missing field | [[1, None]] | [[1, None]] | Passed |
| repeated projection | [[1, 1]] | [[1, 1]] | Passed |
| empty rows | [] | [] | Passed |
| empty projection | [[]] | [[]] | Passed |
SHA-256 / 5e569bfd06fab67ac39e850aaf3585009656161a314d75428a7583ae93355259
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(d):
try:
columns,valid,parent,selection,fields=d
out=[]
for row in selection:
record=[]
for field in fields:
present=field in columns
known=present and all(valid[field])
value=columns[field][row] if present else None
record.append(value if parent[row] and known else None)
out.append(record)
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('gather with field order', solve([{'a': [1, 2], 'b': [3, 4]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[4, 2], [3, 1]])
check('parent hides values', solve([{'a': [1, 2]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [2]])
check('field null lane', solve([{'a': [1, 2]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [2]])
check('missing field', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[1, None]])
check('repeated projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[1, 1]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 2:
check('gather with field order', solve([{'a': [2, 3], 'b': [4, 5]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[5, 3], [4, 2]])
check('parent hides values', solve([{'a': [2, 3]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [3]])
check('field null lane', solve([{'a': [2, 3]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [3]])
check('missing field', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[2, None]])
check('repeated projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[2, 2]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 3:
check('gather with field order', solve([{'a': [3, 4], 'b': [5, 6]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[6, 4], [5, 3]])
check('parent hides values', solve([{'a': [3, 4]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [4]])
check('field null lane', solve([{'a': [3, 4]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [4]])
check('missing field', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[3, None]])
check('repeated projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[3, 3]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 4:
check('gather with field order', solve([{'a': [4, 5], 'b': [6, 7]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[7, 5], [6, 4]])
check('parent hides values', solve([{'a': [4, 5]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [5]])
check('field null lane', solve([{'a': [4, 5]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [5]])
check('missing field', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[4, None]])
check('repeated projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[4, 4]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 5:
check('gather with field order', solve([{'a': [5, 6], 'b': [7, 8]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[8, 6], [7, 5]])
check('parent hides values', solve([{'a': [5, 6]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [6]])
check('field null lane', solve([{'a': [5, 6]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [6]])
check('missing field', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[5, None]])
check('repeated projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[5, 5]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], []]), [[]])
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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| gather with field order | [[4, 2], [3, 1]] | [[4, 2], [3, 1]] | Passed |
| parent hides values | [[None], [2]] | [[None], [2]] | Passed |
| field null lane | [[None], [None]] | [[None], [2]] | Failed |
| missing field | [[1, None]] | [[1, None]] | Passed |
| repeated projection | [[1, 1]] | [[1, 1]] | Passed |
| empty rows | [] | [] | Passed |
| empty projection | [[]] | [[]] | Passed |
SHA-256 / 407fbc7855ef89a0f63a25d61a0ff4d85f2b7d1c004d27e97f760eb1ca71b82d
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(d):
try:
columns,valid,parent,selection,fields=d
out=[]
for row in selection:
record=[]
for field in fields:
present=field in columns
known=present and valid[field][row]
value=columns[field][row] if present else None
record.append(value if parent[row] and known else None)
out.append(record)
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('gather with field order', solve([{'a': [1, 2], 'b': [3, 4]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[4, 2], [3, 1]])
check('parent hides values', solve([{'a': [1, 2]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [2]])
check('field null lane', solve([{'a': [1, 2]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [2]])
check('missing field', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[1, None]])
check('repeated projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[1, 1]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [1]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 2:
check('gather with field order', solve([{'a': [2, 3], 'b': [4, 5]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[5, 3], [4, 2]])
check('parent hides values', solve([{'a': [2, 3]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [3]])
check('field null lane', solve([{'a': [2, 3]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [3]])
check('missing field', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[2, None]])
check('repeated projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[2, 2]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [2]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 3:
check('gather with field order', solve([{'a': [3, 4], 'b': [5, 6]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[6, 4], [5, 3]])
check('parent hides values', solve([{'a': [3, 4]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [4]])
check('field null lane', solve([{'a': [3, 4]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [4]])
check('missing field', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[3, None]])
check('repeated projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[3, 3]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [3]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 4:
check('gather with field order', solve([{'a': [4, 5], 'b': [6, 7]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[7, 5], [6, 4]])
check('parent hides values', solve([{'a': [4, 5]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [5]])
check('field null lane', solve([{'a': [4, 5]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [5]])
check('missing field', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[4, None]])
check('repeated projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[4, 4]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [4]}, {'a': [True]}, [True], [0], []]), [[]])
elif N == 5:
check('gather with field order', solve([{'a': [5, 6], 'b': [7, 8]}, {'a': [True, True], 'b': [True, True]}, [True, True], [1, 0], ['b', 'a']]), [[8, 6], [7, 5]])
check('parent hides values', solve([{'a': [5, 6]}, {'a': [True, True]}, [False, True], [0, 1], ['a']]), [[None], [6]])
check('field null lane', solve([{'a': [5, 6]}, {'a': [False, True]}, [True, True], [0, 1], ['a']]), [[None], [6]])
check('missing field', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'missing']]), [[5, None]])
check('repeated projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], ['a', 'a']]), [[5, 5]])
check('empty rows', solve([{'a': []}, {'a': []}, [], [], ['a']]), [])
check('empty projection', solve([{'a': [5]}, {'a': [True]}, [True], [0], []]), [[]])
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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| gather with field order | [[4, 2], [3, 1]] | [[4, 2], [3, 1]] | Passed |
| parent hides values | [[None], [2]] | [[None], [2]] | Passed |
| field null lane | [[None], [2]] | [[None], [2]] | Passed |
| missing field | [[1, None]] | [[1, None]] | Passed |
| repeated projection | [[1, 1]] | [[1, 1]] | Passed |
| empty rows | [] | [] | Passed |
| empty projection | [[]] | [[]] | Passed |
SHA-256 / d130665f6d9eb307fa1c3d2f5e9140f3d3400bbd3dd72e2baba761a0b23ebff2
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 2026-09-29T14:44:12.517842+00:00.
Case digest / 529b9408c36ad4d87a587b16fe13a502d49217dd96632385791ee3bcd1843534