FA-45601 / Data systems / Open access
CTE lookup searches outer scopes before inner scopes · case 01
CTE lookup searches outer scopes before inner scopes.
ROOT CAUSE
cte-lexical-environments: CTE lookup searches outer scopes before inner scopes.
VERIFIED REPAIR
Preserve the stated physical representation and operation order: Interpret nested query blocks using actions push(definitions), pop, and read(name). Every push opens a new CTE scope; reads search innermost scope first then outer scopes. Empty inner scopes still hide nothing, popping restores outer definitions, and unresolved names yield MISSING. Definitions are already evaluated row lists.
Unsuccessful approach: Restricting lookup to the innermost scope fixes shadowing but prevents outer fallback.
Case contract
Interpret nested query blocks using actions push(definitions), pop, and read(name). Every push opens a new CTE scope; reads search innermost scope first then outer scopes. Empty inner scopes still hide nothing, popping restores outer definitions, and unresolved names yield MISSING. Definitions are already evaluated row lists.
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:
scopes=[{}]; out=[]
for action,arg in d:
if action=='push': scopes.append(dict(arg))
elif action=='pop': scopes.pop()
else:
found='MISSING'
for scope in scopes:
if arg in scope: found=scope[arg]; break
out.append(found)
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('inner shadow', solve([['push', {'x': [1]}], ['push', {'x': [2]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[2], [1]])
check('outer fallback', solve([['push', {'x': [1]}], ['push', {}], ['read', 'x']]), [[1]])
check('empty shadow', solve([['push', {'x': [1]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [1]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [1]}], ['push', {'x': [2]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[1]])
check('no actions', solve([]), [])
elif N == 2:
check('inner shadow', solve([['push', {'x': [2]}], ['push', {'x': [3]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[3], [2]])
check('outer fallback', solve([['push', {'x': [2]}], ['push', {}], ['read', 'x']]), [[2]])
check('empty shadow', solve([['push', {'x': [2]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [2]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [2]}], ['push', {'x': [3]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[2]])
check('no actions', solve([]), [])
elif N == 3:
check('inner shadow', solve([['push', {'x': [3]}], ['push', {'x': [4]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[4], [3]])
check('outer fallback', solve([['push', {'x': [3]}], ['push', {}], ['read', 'x']]), [[3]])
check('empty shadow', solve([['push', {'x': [3]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [3]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [3]}], ['push', {'x': [4]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[3]])
check('no actions', solve([]), [])
elif N == 4:
check('inner shadow', solve([['push', {'x': [4]}], ['push', {'x': [5]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[5], [4]])
check('outer fallback', solve([['push', {'x': [4]}], ['push', {}], ['read', 'x']]), [[4]])
check('empty shadow', solve([['push', {'x': [4]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [4]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [4]}], ['push', {'x': [5]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[4]])
check('no actions', solve([]), [])
elif N == 5:
check('inner shadow', solve([['push', {'x': [5]}], ['push', {'x': [6]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[6], [5]])
check('outer fallback', solve([['push', {'x': [5]}], ['push', {}], ['read', 'x']]), [[5]])
check('empty shadow', solve([['push', {'x': [5]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [5]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [5]}], ['push', {'x': [6]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[5]])
check('no actions', solve([]), [])
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 |
|---|---|---|---|
| inner shadow | [[1], [1]] | [[2], [1]] | Failed |
| outer fallback | [[1]] | [[1]] | Passed |
| empty shadow | [[1]] | [[]] | Failed |
| missing name | ['MISSING'] | ['MISSING'] | Passed |
| restore missing | ['MISSING'] | ['MISSING'] | Passed |
| nested pops | [[1]] | [[1]] | Passed |
| no actions | [] | [] | Passed |
SHA-256 / 56ff06d20787fbc8810273e6f689ea948fed56532b74607dab16590eca8a6719
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(d):
try:
scopes=[{}]; out=[]
for action,arg in d:
if action=='push': scopes.append(dict(arg))
elif action=='pop': scopes.pop()
else:
found='MISSING'
for scope in scopes[-1:]:
if arg in scope: found=scope[arg]; break
out.append(found)
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('inner shadow', solve([['push', {'x': [1]}], ['push', {'x': [2]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[2], [1]])
check('outer fallback', solve([['push', {'x': [1]}], ['push', {}], ['read', 'x']]), [[1]])
check('empty shadow', solve([['push', {'x': [1]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [1]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [1]}], ['push', {'x': [2]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[1]])
check('no actions', solve([]), [])
elif N == 2:
check('inner shadow', solve([['push', {'x': [2]}], ['push', {'x': [3]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[3], [2]])
check('outer fallback', solve([['push', {'x': [2]}], ['push', {}], ['read', 'x']]), [[2]])
check('empty shadow', solve([['push', {'x': [2]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [2]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [2]}], ['push', {'x': [3]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[2]])
check('no actions', solve([]), [])
elif N == 3:
check('inner shadow', solve([['push', {'x': [3]}], ['push', {'x': [4]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[4], [3]])
check('outer fallback', solve([['push', {'x': [3]}], ['push', {}], ['read', 'x']]), [[3]])
check('empty shadow', solve([['push', {'x': [3]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [3]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [3]}], ['push', {'x': [4]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[3]])
check('no actions', solve([]), [])
elif N == 4:
check('inner shadow', solve([['push', {'x': [4]}], ['push', {'x': [5]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[5], [4]])
check('outer fallback', solve([['push', {'x': [4]}], ['push', {}], ['read', 'x']]), [[4]])
check('empty shadow', solve([['push', {'x': [4]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [4]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [4]}], ['push', {'x': [5]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[4]])
check('no actions', solve([]), [])
elif N == 5:
check('inner shadow', solve([['push', {'x': [5]}], ['push', {'x': [6]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[6], [5]])
check('outer fallback', solve([['push', {'x': [5]}], ['push', {}], ['read', 'x']]), [[5]])
check('empty shadow', solve([['push', {'x': [5]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [5]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [5]}], ['push', {'x': [6]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[5]])
check('no actions', solve([]), [])
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 |
|---|---|---|---|
| inner shadow | [[2], [1]] | [[2], [1]] | Passed |
| outer fallback | ['MISSING'] | [[1]] | Failed |
| empty shadow | [[]] | [[]] | Passed |
| missing name | ['MISSING'] | ['MISSING'] | Passed |
| restore missing | ['MISSING'] | ['MISSING'] | Passed |
| nested pops | [[1]] | [[1]] | Passed |
| no actions | [] | [] | Passed |
SHA-256 / 065c73d60a3f465daea384e76813def732224c6d0582db088787ab8b15b312a9
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(d):
try:
scopes=[{}]; out=[]
for action,arg in d:
if action=='push': scopes.append(dict(arg))
elif action=='pop': scopes.pop()
else:
found='MISSING'
for scope in reversed(scopes):
if arg in scope: found=scope[arg]; break
out.append(found)
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('inner shadow', solve([['push', {'x': [1]}], ['push', {'x': [2]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[2], [1]])
check('outer fallback', solve([['push', {'x': [1]}], ['push', {}], ['read', 'x']]), [[1]])
check('empty shadow', solve([['push', {'x': [1]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [1]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [1]}], ['push', {'x': [2]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[1]])
check('no actions', solve([]), [])
elif N == 2:
check('inner shadow', solve([['push', {'x': [2]}], ['push', {'x': [3]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[3], [2]])
check('outer fallback', solve([['push', {'x': [2]}], ['push', {}], ['read', 'x']]), [[2]])
check('empty shadow', solve([['push', {'x': [2]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [2]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [2]}], ['push', {'x': [3]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[2]])
check('no actions', solve([]), [])
elif N == 3:
check('inner shadow', solve([['push', {'x': [3]}], ['push', {'x': [4]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[4], [3]])
check('outer fallback', solve([['push', {'x': [3]}], ['push', {}], ['read', 'x']]), [[3]])
check('empty shadow', solve([['push', {'x': [3]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [3]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [3]}], ['push', {'x': [4]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[3]])
check('no actions', solve([]), [])
elif N == 4:
check('inner shadow', solve([['push', {'x': [4]}], ['push', {'x': [5]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[5], [4]])
check('outer fallback', solve([['push', {'x': [4]}], ['push', {}], ['read', 'x']]), [[4]])
check('empty shadow', solve([['push', {'x': [4]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [4]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [4]}], ['push', {'x': [5]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[4]])
check('no actions', solve([]), [])
elif N == 5:
check('inner shadow', solve([['push', {'x': [5]}], ['push', {'x': [6]}], ['read', 'x'], ['pop', None], ['read', 'x']]), [[6], [5]])
check('outer fallback', solve([['push', {'x': [5]}], ['push', {}], ['read', 'x']]), [[5]])
check('empty shadow', solve([['push', {'x': [5]}], ['push', {'x': []}], ['read', 'x']]), [[]])
check('missing name', solve([['read', 'x']]), ['MISSING'])
check('restore missing', solve([['push', {'x': [5]}], ['pop', None], ['read', 'x']]), ['MISSING'])
check('nested pops', solve([['push', {'x': [5]}], ['push', {'x': [6]}], ['push', {}], ['pop', None], ['pop', None], ['read', 'x']]), [[5]])
check('no actions', solve([]), [])
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 |
|---|---|---|---|
| inner shadow | [[2], [1]] | [[2], [1]] | Passed |
| outer fallback | [[1]] | [[1]] | Passed |
| empty shadow | [[]] | [[]] | Passed |
| missing name | ['MISSING'] | ['MISSING'] | Passed |
| restore missing | ['MISSING'] | ['MISSING'] | Passed |
| nested pops | [[1]] | [[1]] | Passed |
| no actions | [] | [] | Passed |
SHA-256 / 6f6534aa1ff2c258ca2015af67b08f8ac06efa282c875621256588015773afb8
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 2026-09-29T14:44:23.919062+00:00.
Case digest / 0f4f3de66d8391f353d03a4ee51d147cdfc4f3081d8b432ce981040ab09cda28