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FA-45831 / Data systems / Open access

Interval join emits intervals by storage order rather than start order · case 01

Interval join emits intervals by storage order rather than start order.

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

ROOT CAUSE

interval-join-sweep: Interval join emits intervals by storage order rather than start order.

THE FAILURE

interval-join-sweep: Interval join emits intervals by storage order rather than start order.

Unsuccessful approach: Identity-only order fails when interval starts differ.

Case contract

Join probe points [id,key,time] to interval rows [id,key,start,end] under start<=time<end and ordinary non-null key equality. Emit probe-major [probe-id,interval-id] pairs, with matching intervals ordered by (start,id). Empty intervals never match; overlapping intervals all produce rows.

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:
        points,intervals=d
        out=[]
        for ident,key,time in points:
            candidates=intervals
            for other,k,start,end in candidates:
                if key is None or key!=k: continue
                if start<=time and time<end:
                    out.append([ident,other])
        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('end expired', solve([[[10, 'a', 3]], [[20, 'a', 1, 3]]]), [])
    check('start active', solve([[[10, 'a', 1]], [[20, 'a', 1, 3]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 1]], [[20, 'a', 2, 4]]]), [])
    check('overlap order', solve([[[10, 'a', 3]], [[20, 'a', 2, 5], [21, 'a', 1, 4]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 2]], [[20, 'b', 1, 4], [21, None, 1, 4]]]), [])
    check('empty interval', solve([[[10, 'a', 1]], [[20, 'a', 1, 1]]]), [])
    check('null probe', solve([[[10, None, 2]], [[20, None, 1, 4]]]), [])
elif N == 2:
    check('end expired', solve([[[10, 'a', 4]], [[20, 'a', 2, 4]]]), [])
    check('start active', solve([[[10, 'a', 2]], [[20, 'a', 2, 4]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 2]], [[20, 'a', 3, 5]]]), [])
    check('overlap order', solve([[[10, 'a', 4]], [[20, 'a', 3, 6], [21, 'a', 2, 5]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 3]], [[20, 'b', 2, 5], [21, None, 2, 5]]]), [])
    check('empty interval', solve([[[10, 'a', 2]], [[20, 'a', 2, 2]]]), [])
    check('null probe', solve([[[10, None, 3]], [[20, None, 2, 5]]]), [])
elif N == 3:
    check('end expired', solve([[[10, 'a', 5]], [[20, 'a', 3, 5]]]), [])
    check('start active', solve([[[10, 'a', 3]], [[20, 'a', 3, 5]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 3]], [[20, 'a', 4, 6]]]), [])
    check('overlap order', solve([[[10, 'a', 5]], [[20, 'a', 4, 7], [21, 'a', 3, 6]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 4]], [[20, 'b', 3, 6], [21, None, 3, 6]]]), [])
    check('empty interval', solve([[[10, 'a', 3]], [[20, 'a', 3, 3]]]), [])
    check('null probe', solve([[[10, None, 4]], [[20, None, 3, 6]]]), [])
elif N == 4:
    check('end expired', solve([[[10, 'a', 6]], [[20, 'a', 4, 6]]]), [])
    check('start active', solve([[[10, 'a', 4]], [[20, 'a', 4, 6]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 4]], [[20, 'a', 5, 7]]]), [])
    check('overlap order', solve([[[10, 'a', 6]], [[20, 'a', 5, 8], [21, 'a', 4, 7]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 5]], [[20, 'b', 4, 7], [21, None, 4, 7]]]), [])
    check('empty interval', solve([[[10, 'a', 4]], [[20, 'a', 4, 4]]]), [])
    check('null probe', solve([[[10, None, 5]], [[20, None, 4, 7]]]), [])
elif N == 5:
    check('end expired', solve([[[10, 'a', 7]], [[20, 'a', 5, 7]]]), [])
    check('start active', solve([[[10, 'a', 5]], [[20, 'a', 5, 7]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 5]], [[20, 'a', 6, 8]]]), [])
    check('overlap order', solve([[[10, 'a', 7]], [[20, 'a', 6, 9], [21, 'a', 5, 8]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 6]], [[20, 'b', 5, 8], [21, None, 5, 8]]]), [])
    check('empty interval', solve([[[10, 'a', 5]], [[20, 'a', 5, 5]]]), [])
    check('null probe', solve([[[10, None, 6]], [[20, None, 5, 8]]]), [])
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
end expired[][]Passed
start active[[10, 20]][[10, 20]]Passed
future inactive[][]Passed
overlap order[[10, 20], [10, 21]][[10, 21], [10, 20]]Failed
other keys[][]Passed
empty interval[][]Passed
null probe[][]Passed

SHA-256 / 9a05717388cdde586c2227fbbd6042beb2f3761b3b6a62dd8b7669d59572dd38

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(d):
    try:
        points,intervals=d
        out=[]
        for ident,key,time in points:
            candidates=sorted(intervals,key=lambda r:r[0])
            for other,k,start,end in candidates:
                if key is None or key!=k: continue
                if start<=time and time<end:
                    out.append([ident,other])
        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('end expired', solve([[[10, 'a', 3]], [[20, 'a', 1, 3]]]), [])
    check('start active', solve([[[10, 'a', 1]], [[20, 'a', 1, 3]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 1]], [[20, 'a', 2, 4]]]), [])
    check('overlap order', solve([[[10, 'a', 3]], [[20, 'a', 2, 5], [21, 'a', 1, 4]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 2]], [[20, 'b', 1, 4], [21, None, 1, 4]]]), [])
    check('empty interval', solve([[[10, 'a', 1]], [[20, 'a', 1, 1]]]), [])
    check('null probe', solve([[[10, None, 2]], [[20, None, 1, 4]]]), [])
elif N == 2:
    check('end expired', solve([[[10, 'a', 4]], [[20, 'a', 2, 4]]]), [])
    check('start active', solve([[[10, 'a', 2]], [[20, 'a', 2, 4]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 2]], [[20, 'a', 3, 5]]]), [])
    check('overlap order', solve([[[10, 'a', 4]], [[20, 'a', 3, 6], [21, 'a', 2, 5]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 3]], [[20, 'b', 2, 5], [21, None, 2, 5]]]), [])
    check('empty interval', solve([[[10, 'a', 2]], [[20, 'a', 2, 2]]]), [])
    check('null probe', solve([[[10, None, 3]], [[20, None, 2, 5]]]), [])
elif N == 3:
    check('end expired', solve([[[10, 'a', 5]], [[20, 'a', 3, 5]]]), [])
    check('start active', solve([[[10, 'a', 3]], [[20, 'a', 3, 5]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 3]], [[20, 'a', 4, 6]]]), [])
    check('overlap order', solve([[[10, 'a', 5]], [[20, 'a', 4, 7], [21, 'a', 3, 6]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 4]], [[20, 'b', 3, 6], [21, None, 3, 6]]]), [])
    check('empty interval', solve([[[10, 'a', 3]], [[20, 'a', 3, 3]]]), [])
    check('null probe', solve([[[10, None, 4]], [[20, None, 3, 6]]]), [])
elif N == 4:
    check('end expired', solve([[[10, 'a', 6]], [[20, 'a', 4, 6]]]), [])
    check('start active', solve([[[10, 'a', 4]], [[20, 'a', 4, 6]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 4]], [[20, 'a', 5, 7]]]), [])
    check('overlap order', solve([[[10, 'a', 6]], [[20, 'a', 5, 8], [21, 'a', 4, 7]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 5]], [[20, 'b', 4, 7], [21, None, 4, 7]]]), [])
    check('empty interval', solve([[[10, 'a', 4]], [[20, 'a', 4, 4]]]), [])
    check('null probe', solve([[[10, None, 5]], [[20, None, 4, 7]]]), [])
elif N == 5:
    check('end expired', solve([[[10, 'a', 7]], [[20, 'a', 5, 7]]]), [])
    check('start active', solve([[[10, 'a', 5]], [[20, 'a', 5, 7]]]), [[10, 20]])
    check('future inactive', solve([[[10, 'a', 5]], [[20, 'a', 6, 8]]]), [])
    check('overlap order', solve([[[10, 'a', 7]], [[20, 'a', 6, 9], [21, 'a', 5, 8]]]), [[10, 21], [10, 20]])
    check('other keys', solve([[[10, 'a', 6]], [[20, 'b', 5, 8], [21, None, 5, 8]]]), [])
    check('empty interval', solve([[[10, 'a', 5]], [[20, 'a', 5, 5]]]), [])
    check('null probe', solve([[[10, None, 6]], [[20, None, 5, 8]]]), [])
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
end expired[][]Passed
start active[[10, 20]][[10, 20]]Passed
future inactive[][]Passed
overlap order[[10, 20], [10, 21]][[10, 21], [10, 20]]Failed
other keys[][]Passed
empty interval[][]Passed
null probe[][]Passed

SHA-256 / f10ab552072dd719940d98ca23074ab39772bf218e08ed267b26fd752d5064f5

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 2026-09-29T14:44:26.224044+00:00.

Case digest / cf9c4900d694b4ce84b716f283d9475c559027c18f534c399db3d976be790ada