FA-100276 / Dataset deduplication grouping / Open access

Dataset deduplication: deleted record is resurrected by older duplicate · case 01

deleted record is resurrected by older duplicate.

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

ROOT CAUSE

Deduplication filters deletion markers before resolving each key to its newest revision.

THE FAILURE

Deduplication filters deletion markers before resolving each key to its newest revision.

Unsuccessful approach: Treating any tombstone as final hides a later live revision that intentionally restores the key.

Case contract

Rows [key,revision,deleted,payload] have unique key/revision pairs and arbitrary order. Return [key,payload] for each key whose newest revision is not deleted, sorted by key.

Why this case matters

This deterministic toy operation makes one dataset equivalence or representative rule explicit.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(rows):
    latest={}
    for k,r,deleted,payload in rows:
     if not deleted and (k not in latest or r>latest[k][0]): latest[k]=(r,payload)
    return [[k,latest[k][1]] for k in sorted(latest)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
k='item'+str(N)
check('newest tombstone removes key',solve([[k,N,False,'old'],[k,N+1,True,'']]),[])
check('newer live revision restores key',solve([[k,N,True,''],[k,N+1,False,'new']]),[[k,'new']])
check('stale tombstone does not remove later record',solve([[k,N,True,''],[k,N+2,False,'restored']]),[[k,'restored']])
check('unordered latest tombstone',solve([[k,N+2,True,''],[k,N,False,'before']]),[])
check('independent live key',solve([[k,N,True,''],['other',N,False,'keep']]),[['other','keep']])
check('empty history',solve([]),[])
check('single live revision',solve([[k,0,False,'only']]),[[k,'only']])
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
newest tombstone removes key	`[['item1', 'old']]`	`[]`	Failed
newer live revision restores key	`[['item1', 'new']]`	`[['item1', 'new']]`	Passed
stale tombstone does not remove later record	`[['item1', 'restored']]`	`[['item1', 'restored']]`	Passed
unordered latest tombstone	`[['item1', 'before']]`	`[]`	Failed
independent live key	`[['other', 'keep']]`	`[['other', 'keep']]`	Passed
empty history	`[]`	`[]`	Passed
single live revision	`[['item1', 'only']]`	`[['item1', 'only']]`	Passed

SHA-256 / 6a16db7e177cbeeb35e2520dcde70176b8010edc4656171ed47033de841a3c44

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(rows):
    tombstoned={k for k,r,deleted,payload in rows if deleted}
    latest={}
    for k,r,deleted,payload in rows:
     if not deleted and (k not in latest or r>latest[k][0]): latest[k]=(r,payload)
    return [[k,latest[k][1]] for k in sorted(latest) if k not in tombstoned]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
k='item'+str(N)
check('newest tombstone removes key',solve([[k,N,False,'old'],[k,N+1,True,'']]),[])
check('newer live revision restores key',solve([[k,N,True,''],[k,N+1,False,'new']]),[[k,'new']])
check('stale tombstone does not remove later record',solve([[k,N,True,''],[k,N+2,False,'restored']]),[[k,'restored']])
check('unordered latest tombstone',solve([[k,N+2,True,''],[k,N,False,'before']]),[])
check('independent live key',solve([[k,N,True,''],['other',N,False,'keep']]),[['other','keep']])
check('empty history',solve([]),[])
check('single live revision',solve([[k,0,False,'only']]),[[k,'only']])
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
newest tombstone removes key	`[]`	`[]`	Passed
newer live revision restores key	`[]`	`[['item1', 'new']]`	Failed
stale tombstone does not remove later record	`[]`	`[['item1', 'restored']]`	Failed
unordered latest tombstone	`[]`	`[]`	Passed
independent live key	`[['other', 'keep']]`	`[['other', 'keep']]`	Passed
empty history	`[]`	`[]`	Passed
single live revision	`[['item1', 'only']]`	`[['item1', 'only']]`	Passed

SHA-256 / 0a77a9980a1952566c2f728933e50a30e5d5f5f9c36438fc921a8dc700a7faf9

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.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

Inputs are small in-memory fixtures with the stated contract; results do not claim production deduplication quality. 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 2026-09-30T16:48:33.592513+00:00.

Case digest / d0b64673ae902ecbcbf3a243b2d90d30d84f7f99eb0a79ba93d1b2e55da12682