Execution Plan
Visualize how BigQuery processed your query to identify performance bottlenecks.
Accessing the Plan
- Execute a query
- Click "View Execution Plan" in results section
Or from Query History: select a query → "View Execution Plan"
What It Shows
Stage Diagram
┌──────────────────┐
│ Stage 1: Read │
│ 45.2 GB read │
│ 2.3s │
└────────┬─────────┘
▼
┌──────────────────┐
│ Stage 2: Filter │
│ 1.2 GB output │
│ 0.8s │
└──────────────────┘
Timeline View
Stage 1: ████████████████ 2.3s
Stage 2: ████████ 0.8s
Stage 3: ██████████ 1.1s
Stage Types
| Stage | What It Does | Optimization |
|---|---|---|
| Read | Scan table data | Add partition/cluster filters |
| Filter | Apply WHERE | Push filters to Read stage |
| Join | Combine tables | Filter before joining |
| Aggregate | GROUP BY | Reduce cardinality |
| Sort | ORDER BY | Add LIMIT, remove if not needed |
Red Flags
- Shuffle > Input: Inefficient data movement
- One stage 80%+ of time: Bottleneck
- Output >> Input: Cross join or data explosion