Nearest Analysis Worker

Processes nearest neighbor analysis jobs between two datasets.

Overview

The nearest analysis worker finds the nearest features from a target dataset for each feature in a source dataset.

Job Type

nearest

Input Parameters

{
  "source_dataset_id": 123,
  "target_dataset_id": 124,
  "max_distance": 5000,
  "limit": 1
}

Parameters

  • source_dataset_id (required): Source dataset ID

  • target_dataset_id (required): Target dataset ID

  • max_distance (optional): Maximum search distance in dataset units

  • limit (optional): Maximum neighbors per feature (default: 1)

Output

Creates a new dataset with nearest neighbor results:

  • Original source feature geometry

  • Nearest target feature information

  • Distance to nearest neighbor

  • Attributes from both source and target features

Algorithm

The worker uses PostGIS functions to:

  1. For each source feature, find nearest target features

  2. Calculate distances using spatial indexes

  3. Apply distance and limit constraints

  4. Join attributes from both datasets

  5. Store results in output table

Example

# Enqueue a nearest analysis job via API
curl -X POST "https://example.com/api/nearest_run.php" \
  -H "Content-Type: application/json" \
  -d '{
    "source_dataset_id": 123,
    "target_dataset_id": 124,
    "max_distance": 5000,
    "limit": 1
  }'

# Worker processes the job automatically

Background Jobs

This analysis runs as a background job. The worker:

  1. Fetches queued nearest jobs

  2. Validates input parameters

  3. Executes PostGIS nearest neighbor queries

  4. Creates output dataset

  5. Marks job as completed

Performance Considerations

  • Processing time depends on dataset sizes

  • Spatial indexes are critical for performance

  • Large max_distance values may slow processing

  • Consider limiting results per feature