Using Dry-Run Mode

Dry-run mode lets you preview compression impact without making any changes to your index.

What is Dry-Run?

When you set dry_run=True, Gilial:

• Analyzes your vectors
• Calculates which vectors would be deleted
• Reports estimated savings
• Does NOT delete anything

Basic Usage

curl -X POST http://localhost:8000/compress \
  -H "Content-Type: application/json" \
  -d '{"strategy": "balanced", "dry_run": true}'

Understanding the Results

The response includes:

{
  "original_vectors": 10000,
  "compressed_vectors": 9739,
  "original_size_mb": 29.30,
  "compressed_size_mb": 28.53,
  "compression_ratio": 0.974,
  "savings_pct": 2.61
}

• original_vectors - Starting vector count
• compressed_vectors - Vectors after compression
• savings_pct - Percentage of space saved
• compression_ratio - New size / original size

Workflow Example

# Step 1: Estimate savings
curl http://localhost:8000/estimate?strategy=balanced

# Step 2: Dry-run to confirm
curl -X POST http://localhost:8000/compress \
  -H "Content-Type: application/json" \
  -d '{"strategy": "balanced", "dry_run": true}'

# Step 3: Apply if happy (if savings > 2%)
curl -X POST http://localhost:8000/compress \
  -H "Content-Type: application/json" \
  -d '{"strategy": "balanced", "dry_run": false}'

Best Practices

1. Always dry-run first - Never jump to dry_run=False
2. Review the numbers - Check if savings justify the deletion
3. Use for testing - Test compression strategies on a copy before applying
4. Monitor queries - Run dry-run before and after to spot impact
5. Document changes - Keep records of compression runs

Common Dry-Run Patterns

Check Before Every Compression

Always dry-run first before applying:

# Dry-run
curl -X POST http://localhost:8000/compress \
  -d '{"strategy": "balanced", "dry_run": true}' | jq '.savings_pct'

# Only apply if savings look good
curl -X POST http://localhost:8000/compress \
  -d '{"strategy": "balanced", "dry_run": false}'

Compare Strategies

Test both strategies to see which gives better results:

# Test balanced
curl -X POST http://localhost:8000/compress \
  -d '{"strategy": "balanced", "dry_run": true}' | jq '.savings_pct'

# Test aggressive
curl -X POST http://localhost:8000/compress \
  -d '{"strategy": "aggressive", "dry_run": true}' | jq '.savings_pct'