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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:

For each source feature, find nearest target features
Calculate distances using spatial indexes
Apply distance and limit constraints
Join attributes from both datasets
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:

Fetches queued nearest jobs
Validates input parameters
Executes PostGIS nearest neighbor queries
Creates output dataset
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

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