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Cheatsheet: Capacity Metrics, Monitoring & Troubleshooting

Cheatsheet: Capacity Metrics, Monitoring & Troubleshooting

Source

  • Content type: Quick-Reference Cheatsheet
  • Target Exam: Exam DP-700
  • Date captured: 2026-08-15
  • Last reviewed: 2026-08-15

1. Capacity Smoothing & Throttling Rules

┌────────────────────────────────────────────────────────┐
│               Fabric Capacity Smoothing                │
├──────────────────────────┬─────────────────────────────┤
│ Interactive Operations   │ 5-minute moving average     │
│ Background Operations    │ 24-hour moving average      │
└──────────────────────────┴─────────────────────────────┘


┌────────────────────────────────────────────────────────┐
│              Throttling Escalation Order               │
├──────────────────────────┬─────────────────────────────┤
│ 1. Interactive Delay     │ > 10 min burndown debt      │
│ 2. Interactive Rejection │ > 60 min burndown debt      │
│ 3. Background Rejection  │ > 24 hr persistent overload │
└──────────────────────────┴─────────────────────────────┘

2. Spark Job Diagnosis & Remediation

SymptomProbable CauseDiagnostic ToolRecommended Solution
99 tasks finish in seconds, 1 task takes 15 minsData SkewSpark UI Stage TimelineApply salt keys, or enable spark.sql.adaptive.skewJoin.enabled
Spark job fails with OutOfMemoryError (OOM)Memory Pressure / Disk SpillSpark UI Executor Memory GraphIncrease node size, reduce shuffle partitions, avoid collecting massive DataFrames (df.collect())
Massive small file buildupUnmanaged frequent appendsOneLake file explorerRun OPTIMIZE <table> VORDER;
Query fails after retention cleanupVACUUM executed within time travel windowError log (FileNotFoundException)Increase VACUUM RETAIN <N> HOURS retention period

3. Warehouse Query Tuning

  • Check queryinsights.exec_requests_history for long duration or high CPU time.
  • Avoid non-sargable functions in WHERE clauses (e.g. WHERE YEAR(OrderDate) = 2026 $\rightarrow$ use WHERE OrderDate >= '2026-01-01' AND OrderDate < '2027-01-01').
  • Ensure auto-create statistics is active.