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WEIGHTED SUM Billable Metric

Step-by-Step Setup When creating a WEIGHTED SUM-based metered feature:
  1. Navigate to Features
    • Go to Product Catalog → Features
    • Click “Add Feature”
  2. Basic Information
    • Name: “Reserved Storage” (or descriptive name)
    • Type: Select “Metered”
  3. Event Configuration
    • Event Name: storage.reserved (must match your event data)
    • Aggregation Function: Weighted Sum
    • Aggregation Field: gb_reserved (the property to weight by time)
  4. Usage Settings
    • Usage Reset: Periodic (for capacity-based billing)
    • Unit Name: GB-time (time-weighted unit)
  5. Save Feature

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Calculation Example

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Billing Period

Period: July 31, 2025 18:30:00 UTC to August 31, 2025 18:30:00 UTC
Total period duration: 31 days = 2,678,400 seconds

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Event Data

[
  {
    "event_id": "evt_001",
    "event_name": "storage.reserved",
    "external_customer_id": "customer_123",
    "timestamp": "2025-08-16T00:00:00Z",
    "properties": {
      "gb_reserved": 20
    }
  },
  {
    "event_id": "evt_002",
    "event_name": "storage.reserved",
    "external_customer_id": "customer_123",
    "timestamp": "2025-08-18T00:00:00Z",
    "properties": {
      "gb_reserved": 10
    }
  },
  {
    "event_id": "evt_003",
    "event_name": "storage.reserved",
    "external_customer_id": "customer_123",
    "timestamp": "2025-08-20T00:00:00Z",
    "properties": {
      "gb_reserved": 10
    }
  },
  {
    "event_id": "evt_004",
    "event_name": "storage.reserved",
    "external_customer_id": "customer_123",
    "timestamp": "2025-08-25T00:00:00Z",
    "properties": {
      "gb_reserved": 5
    }
  }
]

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Weighted Sum Formula

weighted_value = (property_value / total_period_seconds) × seconds_from_event_to_period_end

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Calculation Process

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Event 1: August 16, 2025 - 20 GB

  • Event timestamp: August 16, 2025 00:00:00 UTC
  • Seconds until period end: August 31 18:30:00 - August 16 00:00:00 = 15 days, 18.5 hours = 1,365,300 seconds
  • Weighted contribution: (20 / 2,678,400) × 1,365,300 = (20 × 1,365,300) / 2,678,400 = 27,306,000 / 2,678,400 = 10.198660714285714 GB

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Event 2: August 18, 2025 - 10 GB

  • Event timestamp: August 18, 2025 00:00:00 UTC
  • Seconds until period end: August 31 18:30:00 - August 18 00:00:00 = 13 days, 18.5 hours = 1,197,300 seconds
  • Weighted contribution: (10 / 2,678,400) × 1,197,300 = (10 × 1,197,300) / 2,678,400 = 11,973,000 / 2,678,400 = 4.470982142857143 GB

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Event 3: August 20, 2025 - 10 GB

  • Event timestamp: August 20, 2025 00:00:00 UTC
  • Seconds until period end: August 31 18:30:00 - August 20 00:00:00 = 11 days, 18.5 hours = 1,029,300 seconds
  • Weighted contribution: (10 / 2,678,400) × 1,029,300 = (10 × 1,029,300) / 2,678,400 = 10,293,000 / 2,678,400 = 3.843303571428571 GB

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Event 4: August 25, 2025 - 5 GB

  • Event timestamp: August 25, 2025 00:00:00 UTC
  • Seconds until period end: August 31 18:30:00 - August 25 00:00:00 = 6 days, 18.5 hours = 573,300 seconds
  • Weighted contribution: (5 / 2,678,400) × 573,300 = (5 × 573,300) / 2,678,400 = 2,866,500 / 2,678,400 = 1.070200892857143 GB

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Total Weighted Sum

10.198660714285714 + 4.470982142857143 + 3.843303571428571 + 1.070200892857143 = 19.583147321428571 GB Result: 19.583147321428571 GB-time

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Use Cases

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Reserved Capacity Billing

Perfect for: Cloud storage reservations, compute capacity, bandwidth reservations 
{
  "event_name": "capacity.reserved",
  "external_customer_id": "acme_corp",
  "properties": {
    "cpu_cores": 8
  }
}

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Time-Based Resource Usage

Perfect for: Database connections, server instances, license usage 
{
  "event_name": "database.connection",
  "external_customer_id": "user_456",
  "properties": {
    "connection_count": 5
  }
}

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Subscription Changes

Perfect for: Mid-cycle plan changes, prorated upgrades/downgrades 
{
  "event_name": "plan.upgrade",
  "external_customer_id": "merchant_789",
  "properties": {
    "new_tier_level": 3
  }
}

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Infrastructure Provisioning

Perfect for: VM instances, container resources, network bandwidth 
{
  "event_name": "vm.provisioned",
  "external_customer_id": "customer_101",
  "properties": {
    "memory_gb": 16
  }
}

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License Allocation

Perfect for: Software seats, user licenses, feature entitlements 
{
  "event_name": "license.allocated",
  "external_customer_id": "enterprise_user",
  "properties": {
    "seat_count": 25
  }
}

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When to Use WEIGHTED SUM

✅ Use WEIGHTED SUM when:
  • Billing for reserved or allocated capacity
  • Need time-proportional calculations
  • Handling mid-cycle subscription changes
  • Measuring sustained resource usage over time
  • Events earlier in the period have more time remaining and get higher weight

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Key Characteristics

  • Time-weighted calculation - Events earlier in the period have higher impact
  • Perfect for capacity billing - Bills based on how long resources were allocated
  • Handles subscription changes - Automatically prorates usage changes
  • Complex formula - More computationally intensive than other aggregations

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Next Steps