Plan değişimi P441

(@BatchSize int,@LeaseSeconds int)WITH c AS (
        SELECT TOP (@BatchSize) *
        FROM rag.EmbedQueue WITH (READPAST, UPDLOCK, ROWLOCK)
        WHERE Status = 'Queued' OR (Status = 'Running' AND LeaseUntilUtc < DBA.fn_Now())
        -- Vaka/KB önce: bekçi her gün binlerce profili kuyruğa alır, onaydan sonra gelen vaka onların ardında beklemesin
        ORDER BY CASE SourceType WHEN 'Profile' THEN 1 ELSE 0 END, QueueID
    )
    UPDATE c SET Status = 'Running', Attempt = Attempt + 1, LeaseUntilUtc = DATEADD(second, @LeaseSeconds, DBA.fn_Now())
    OUTPUT inserted.QueueID, inserted.SourceType, inserted.SourceRef, inserted.Attempt

Plan change case #P441 | DB: DB-11 | Regression | Confidence: Medium (review pending)
Query: (@BatchSize int,@LeaseSeconds int)WITH c AS ( SELECT TOP (@BatchSize) * FROM rag.EmbedQueue WITH (READPAST, UPDLOCK, ROWLOCK) WHERE Status = ? OR (Status = ? AND LeaseUntilUtc < DBA.fn_Now()) ORDER BY CASE SourceType WHEN ? THEN ? ELSE ? END, QueueID ) UPDATE c SET Status = ?, Attempt = Attempt + ?, LeaseUntilUtc = DATEADD(second, @LeaseSeconds, DBA.fn_Now()) OUTPUT inserted.QueueID, inserted.SourceType, inserted.SourceRef, inserted.Attempt
Change: 2026-10-07 13:00 UTC, plan 65163 → 65713, pattern: Transition
Impact (Query Store, per execution): duration 0.7 → 18.4 ms (+2584%); CPU 0.7 → 18.3 ms (+2564%); reads 30 → 1,384 (+4524%); rows 2 → 2.59 (+30%)
Plan difference: Access only in the old plan: rag.EmbedQueue Table Update; rag.EmbedQueue Table Scan; Access only in the new plan: rag.EmbedQueue Index Update [UX_EmbedQueue_Pending]; rag.EmbedQueue Clustered Index Update [PK_EmbedQueue]; rag.EmbedQueue Clustered Index Scan [PK_EmbedQueue]; Estimated cost: 0.038 → 1.129; estimated rows: 2 → 100
Candidate cause: STATS — Statistic rag.EmbedQueue.PK_EmbedQueue was updated 2026-10-07 10:26 (sampled 96.6%); 3 updates in the window; the plans use this statistic.
Candidate cause: STATS — Statistic rag.EmbedQueue.IX_EmbedQueue_Status was updated 2026-10-06 22:15 (sampled 100%); 3 updates in the window; the plans use this statistic.
Candidate cause: STATS — Statistic rag.EmbedQueue.UX_EmbedQueue_Pending was updated 2026-10-05 20:20 (sampled 100%); the plans use this statistic.
Counter-evidence: ORDER_UNCERTAIN — MODULE candidate ruled out: the time of the rag.usp_EmbedQueue_Dequeue event (between 2026-10-06 22:14 and 2026-10-07 20:39) spans the change, so whether it happened before or after is unknown.
Counter-evidence: LOW_SAMPLE — The old plan ran only 28 times: the sample is small and the average is weak.
Confidence rationale: Medium: a single candidate (STATS), not mechanical (no direct link to the plan is proven). Weak counter-evidence: LOW_SAMPLE.
Note: this is a candidate cause, not proof of the root cause.