PostGIS
Mobile
QGIS
MapBender
GeoServer
GeoNode
GeoNetwork
Novella
Solutions
110 lines
2.6 KiB
Markdown
110 lines
2.6 KiB
Markdown
# Dissolve Worker
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Processes dissolve operations to merge features based on attribute values.
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## Overview
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The dissolve worker merges adjacent or overlapping features that share the same attribute value, optionally aggregating numeric fields.
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## Job Type
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`dissolve`
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## Input Parameters
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```json
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{
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"source_dataset_id": 123,
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"output_dataset_id": 124,
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"dissolve_mode": "field",
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"dissolve_field": "category",
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"aggregation_fields": {
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"population": "sum",
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"area": "sum"
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}
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}
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```
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### Parameters
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- `source_dataset_id` (required): Source dataset ID
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- `output_dataset_id` (required): Output dataset ID
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- `dissolve_mode` (optional): "all", "field", or "custom" (default: "field")
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- `dissolve_field` (required if mode="field"): Field to dissolve on
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- `custom_field` (required if mode="custom"): Field for custom grouping
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- `custom_groups` (required if mode="custom"): Array of group definitions
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- `aggregation_fields` (optional): Object mapping field names to aggregation functions (sum, avg, min, max, count)
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## Output
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Creates a new dataset with dissolved features:
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- Merged geometries for each group
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- Aggregated attribute values
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- Group identifiers
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## Dissolve Modes
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### All Features
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Merge all features into a single feature. No grouping field required.
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### By Field
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Merge features that share the same value in the specified field.
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### Custom Groups
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Merge features based on custom group definitions. Allows complex grouping logic.
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## Aggregation Functions
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- `sum`: Sum of numeric values
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- `avg`: Average of numeric values
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- `min`: Minimum value
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- `max`: Maximum value
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- `count`: Count of features
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## Example
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```bash
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# Enqueue a dissolve job via API
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curl -X POST "https://example.com/api/run_dissolve.php" \
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-H "Content-Type: application/json" \
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-d '{
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"source_dataset_id": 123,
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"output_dataset_id": 124,
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"dissolve_mode": "field",
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"dissolve_field": "category",
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"aggregation_fields": {
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"population": "sum",
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"area": "sum"
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}
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}'
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```
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## Background Jobs
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This analysis runs as a background job. The worker:
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1. Fetches queued `dissolve` jobs
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2. Validates input parameters
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3. Executes PostGIS dissolve queries
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4. Applies aggregations
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5. Creates output dataset
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6. Marks job as completed
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## Performance Considerations
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- Processing time depends on dataset size and number of groups
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- Complex geometries may slow processing
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- Aggregation operations add processing time
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- Consider simplifying geometries before dissolving
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## Related Documentation
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- [Dissolve Analysis Tool](../analysis-tools/dissolve.md)
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- [Analysis API](../api/analysis.md)
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- [Workers Overview](index.md)
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