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FA-44681 / Data systems / Open access

Filtered updates emit unchanged rows as spurious changes · case 01

Filtered updates emit unchanged rows as spurious changes.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

delta-filter-before-after: Filtered updates emit unchanged rows as spurious changes.

THE FAILURE

delta-filter-before-after: Filtered updates emit unchanged rows as spurious changes.

Unsuccessful approach: Suppressing all in-filter updates loses changed values.

Case contract

Convert a sequence of [id,before,after] updates into signed filtered rows, with None denoting absent row. The predicate is value>=cutoff. Emit qualifying before-images negatively before qualifying after-images positively; suppress unchanged qualifying values.

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:
        cutoff,updates=d
        out=[]
        for ident,before,after in updates:
            old=before is not None and before>=cutoff
            new=after is not None and after>=cutoff
            if False: continue
            if old: out.append([ident,before,-1])
            if new: out.append([ident,after,1])
        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('leaves filter', solve([1, [[7, 3, 0]]]), [[7, 3, -1]])
    check('enters filter', solve([1, [[7, 0, 3]]]), [[7, 3, 1]])
    check('changes within filter', solve([1, [[7, 2, 3]]]), [[7, 2, -1], [7, 3, 1]])
    check('unchanged', solve([1, [[7, 1, 1]]]), [])
    check('insert', solve([1, [[7, None, 2]]]), [[7, 2, 1]])
    check('delete', solve([1, [[7, 2, None]]]), [[7, 2, -1]])
    check('outside both', solve([1, [[7, -1, 0]]]), [])
    check('no updates', solve([1, []]), [])
elif N == 2:
    check('leaves filter', solve([2, [[7, 4, 1]]]), [[7, 4, -1]])
    check('enters filter', solve([2, [[7, 1, 4]]]), [[7, 4, 1]])
    check('changes within filter', solve([2, [[7, 3, 4]]]), [[7, 3, -1], [7, 4, 1]])
    check('unchanged', solve([2, [[7, 2, 2]]]), [])
    check('insert', solve([2, [[7, None, 3]]]), [[7, 3, 1]])
    check('delete', solve([2, [[7, 3, None]]]), [[7, 3, -1]])
    check('outside both', solve([2, [[7, 0, 1]]]), [])
    check('no updates', solve([2, []]), [])
elif N == 3:
    check('leaves filter', solve([3, [[7, 5, 2]]]), [[7, 5, -1]])
    check('enters filter', solve([3, [[7, 2, 5]]]), [[7, 5, 1]])
    check('changes within filter', solve([3, [[7, 4, 5]]]), [[7, 4, -1], [7, 5, 1]])
    check('unchanged', solve([3, [[7, 3, 3]]]), [])
    check('insert', solve([3, [[7, None, 4]]]), [[7, 4, 1]])
    check('delete', solve([3, [[7, 4, None]]]), [[7, 4, -1]])
    check('outside both', solve([3, [[7, 1, 2]]]), [])
    check('no updates', solve([3, []]), [])
elif N == 4:
    check('leaves filter', solve([4, [[7, 6, 3]]]), [[7, 6, -1]])
    check('enters filter', solve([4, [[7, 3, 6]]]), [[7, 6, 1]])
    check('changes within filter', solve([4, [[7, 5, 6]]]), [[7, 5, -1], [7, 6, 1]])
    check('unchanged', solve([4, [[7, 4, 4]]]), [])
    check('insert', solve([4, [[7, None, 5]]]), [[7, 5, 1]])
    check('delete', solve([4, [[7, 5, None]]]), [[7, 5, -1]])
    check('outside both', solve([4, [[7, 2, 3]]]), [])
    check('no updates', solve([4, []]), [])
elif N == 5:
    check('leaves filter', solve([5, [[7, 7, 4]]]), [[7, 7, -1]])
    check('enters filter', solve([5, [[7, 4, 7]]]), [[7, 7, 1]])
    check('changes within filter', solve([5, [[7, 6, 7]]]), [[7, 6, -1], [7, 7, 1]])
    check('unchanged', solve([5, [[7, 5, 5]]]), [])
    check('insert', solve([5, [[7, None, 6]]]), [[7, 6, 1]])
    check('delete', solve([5, [[7, 6, None]]]), [[7, 6, -1]])
    check('outside both', solve([5, [[7, 3, 4]]]), [])
    check('no updates', solve([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
leaves filter[[7, 3, -1]][[7, 3, -1]]Passed
enters filter[[7, 3, 1]][[7, 3, 1]]Passed
changes within filter[[7, 2, -1], [7, 3, 1]][[7, 2, -1], [7, 3, 1]]Passed
unchanged[[7, 1, -1], [7, 1, 1]][]Failed
insert[[7, 2, 1]][[7, 2, 1]]Passed
delete[[7, 2, -1]][[7, 2, -1]]Passed
outside both[][]Passed
no updates[][]Passed

SHA-256 / d26570eba1d67df6ef7f43d79ec831956d6c69f6fa23cd52cd960d008c561f0c

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(d):
    try:
        cutoff,updates=d
        out=[]
        for ident,before,after in updates:
            old=before is not None and before>=cutoff
            new=after is not None and after>=cutoff
            if old and new: continue
            if old: out.append([ident,before,-1])
            if new: out.append([ident,after,1])
        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('leaves filter', solve([1, [[7, 3, 0]]]), [[7, 3, -1]])
    check('enters filter', solve([1, [[7, 0, 3]]]), [[7, 3, 1]])
    check('changes within filter', solve([1, [[7, 2, 3]]]), [[7, 2, -1], [7, 3, 1]])
    check('unchanged', solve([1, [[7, 1, 1]]]), [])
    check('insert', solve([1, [[7, None, 2]]]), [[7, 2, 1]])
    check('delete', solve([1, [[7, 2, None]]]), [[7, 2, -1]])
    check('outside both', solve([1, [[7, -1, 0]]]), [])
    check('no updates', solve([1, []]), [])
elif N == 2:
    check('leaves filter', solve([2, [[7, 4, 1]]]), [[7, 4, -1]])
    check('enters filter', solve([2, [[7, 1, 4]]]), [[7, 4, 1]])
    check('changes within filter', solve([2, [[7, 3, 4]]]), [[7, 3, -1], [7, 4, 1]])
    check('unchanged', solve([2, [[7, 2, 2]]]), [])
    check('insert', solve([2, [[7, None, 3]]]), [[7, 3, 1]])
    check('delete', solve([2, [[7, 3, None]]]), [[7, 3, -1]])
    check('outside both', solve([2, [[7, 0, 1]]]), [])
    check('no updates', solve([2, []]), [])
elif N == 3:
    check('leaves filter', solve([3, [[7, 5, 2]]]), [[7, 5, -1]])
    check('enters filter', solve([3, [[7, 2, 5]]]), [[7, 5, 1]])
    check('changes within filter', solve([3, [[7, 4, 5]]]), [[7, 4, -1], [7, 5, 1]])
    check('unchanged', solve([3, [[7, 3, 3]]]), [])
    check('insert', solve([3, [[7, None, 4]]]), [[7, 4, 1]])
    check('delete', solve([3, [[7, 4, None]]]), [[7, 4, -1]])
    check('outside both', solve([3, [[7, 1, 2]]]), [])
    check('no updates', solve([3, []]), [])
elif N == 4:
    check('leaves filter', solve([4, [[7, 6, 3]]]), [[7, 6, -1]])
    check('enters filter', solve([4, [[7, 3, 6]]]), [[7, 6, 1]])
    check('changes within filter', solve([4, [[7, 5, 6]]]), [[7, 5, -1], [7, 6, 1]])
    check('unchanged', solve([4, [[7, 4, 4]]]), [])
    check('insert', solve([4, [[7, None, 5]]]), [[7, 5, 1]])
    check('delete', solve([4, [[7, 5, None]]]), [[7, 5, -1]])
    check('outside both', solve([4, [[7, 2, 3]]]), [])
    check('no updates', solve([4, []]), [])
elif N == 5:
    check('leaves filter', solve([5, [[7, 7, 4]]]), [[7, 7, -1]])
    check('enters filter', solve([5, [[7, 4, 7]]]), [[7, 7, 1]])
    check('changes within filter', solve([5, [[7, 6, 7]]]), [[7, 6, -1], [7, 7, 1]])
    check('unchanged', solve([5, [[7, 5, 5]]]), [])
    check('insert', solve([5, [[7, None, 6]]]), [[7, 6, 1]])
    check('delete', solve([5, [[7, 6, None]]]), [[7, 6, -1]])
    check('outside both', solve([5, [[7, 3, 4]]]), [])
    check('no updates', solve([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
leaves filter[[7, 3, -1]][[7, 3, -1]]Passed
enters filter[[7, 3, 1]][[7, 3, 1]]Passed
changes within filter[][[7, 2, -1], [7, 3, 1]]Failed
unchanged[][]Passed
insert[[7, 2, 1]][[7, 2, 1]]Passed
delete[[7, 2, -1]][[7, 2, -1]]Passed
outside both[][]Passed
no updates[][]Passed

SHA-256 / db38d292fca2a01006022386bd56fc5aff2a4444722bbd5aba88763affaf9892

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 8 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 2026-09-29T14:44:14.755280+00:00.

Case digest / 224d108f11f0cf527dd9d4f37e07f5958d3e27bd62e044d5726447b60afcb89a