satellite-provider/_docs/02_document/data_model.md

# Satellite Provider — Data Model

## Entity-Relationship Diagram

```mermaid
erDiagram
    TILES {
        uuid id PK
        int tile_zoom
        float latitude
        float longitude
        float tile_size_meters
        int tile_size_pixels
        varchar image_type
        varchar maps_version
        int version
        varchar source
        timestamp captured_at
        varchar file_path
        int tile_x
        int tile_y
        timestamp created_at
        timestamp updated_at
    }

    REGIONS {
        uuid id PK
        float latitude
        float longitude
        float size_meters
        int zoom_level
        varchar status
        bool stitch_tiles
        varchar csv_file_path
        varchar summary_file_path
        int tiles_downloaded
        int tiles_reused
        timestamp created_at
        timestamp updated_at
    }

    ROUTES {
        uuid id PK
        varchar name
        text description
        float region_size_meters
        int zoom_level
        float total_distance_meters
        int total_points
        bool request_maps
        bool maps_ready
        bool create_tiles_zip
        varchar tiles_zip_path
        varchar csv_file_path
        varchar summary_file_path
        varchar stitched_image_path
        timestamp created_at
        timestamp updated_at
    }

    ROUTE_POINTS {
        uuid id PK
        uuid route_id FK
        int sequence_number
        float latitude
        float longitude
        varchar point_type
        int segment_index
        float distance_from_previous
        timestamp created_at
    }

    ROUTE_REGIONS {
        uuid route_id FK
        uuid region_id FK
        bool is_geofence
        int geofence_polygon_index
        timestamp created_at
    }

    ROUTES ||--o{ ROUTE_POINTS : "has many"
    ROUTES ||--o{ ROUTE_REGIONS : "has many"
    REGIONS ||--o{ ROUTE_REGIONS : "linked via"
```

## Tables

### tiles

Stores metadata for downloaded satellite imagery tiles. Each tile is a single image at a specific geographic coordinate and zoom level.

| Column | Type | Constraints | Description |
|--------|------|-------------|-------------|
| id | UUID | PK | Unique tile identifier |
| tile_zoom | INT | NOT NULL | Google Maps zoom level (1-20) |
| latitude | DOUBLE PRECISION | NOT NULL | Center latitude |
| longitude | DOUBLE PRECISION | NOT NULL | Center longitude |
| tile_size_meters | DOUBLE PRECISION | NOT NULL | Ground coverage in meters |
| tile_size_pixels | INT | NOT NULL | Image dimension in pixels |
| image_type | VARCHAR(10) | NOT NULL | Image format (e.g., "jpg") |
| maps_version | VARCHAR(50) | | Legacy free-form provider tag; post-AZ-373 new rows write NULL. Vestigial post-AZ-484 (column retained for forensics on pre-existing rows; no longer part of any index) |
| version | INT | NOT NULL, DEFAULT 2025 | Year-based versioning for cache invalidation. Vestigial post-AZ-484 — removed from the unique key by migration 012 (preparation for AZ-484); column retained nullable for backward compatibility |
| source | VARCHAR(32) | NOT NULL, DEFAULT 'google_maps' | AZ-484: producer of the imagery (`'google_maps'`, `'uav'`). Closed value set — see `tile-storage` v1.0.0 contract Inv-5 and `Common.Enums.TileSourceConverter`. Backfilled to `'google_maps'` for all pre-AZ-484 rows by migration 013 |
| captured_at | TIMESTAMP | NOT NULL | AZ-484: imagery acquisition timestamp (UTC). Drives most-recent-across-sources selection. Backfilled to `created_at` for pre-AZ-484 rows by migration 013 |
| file_path | VARCHAR(500) | NOT NULL | Relative path to stored image |
| tile_x | INT | NOT NULL | Tile X coordinate (Slippy Map) |
| tile_y | INT | NOT NULL | Tile Y coordinate (Slippy Map) |
| created_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |
| updated_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |

**Indexes** (post-AZ-484):
- `idx_tiles_unique_location_source` UNIQUE (latitude, longitude, tile_zoom, tile_size_meters, source) — created by migration 013; replaces the pre-AZ-484 4-col `idx_tiles_unique_location` (which itself superseded the legacy 5-col `(…, version)` index dropped by migration 012)
- `idx_tiles_coordinates` (tile_zoom, tile_x, tile_y, version)
- `idx_tiles_zoom` (tile_zoom)

**Selection rule**: `GetByTileCoordinatesAsync` and `GetTilesByRegionAsync` return the most-recent row across sources for any `(latitude, longitude, tile_zoom, tile_size_meters)` cell. Tie-break: `captured_at DESC, updated_at DESC, id DESC`. Region read uses `DISTINCT ON` to enforce one-row-per-cell at the SQL layer.

**UPSERT contract**: `INSERT … ON CONFLICT (latitude, longitude, tile_zoom, tile_size_meters, source) DO UPDATE` — same-source re-insert refreshes `file_path, tile_x, tile_y, captured_at, updated_at`. Two producers for the same cell coexist as separate rows.

### regions

Tracks region download requests and their processing status.

| Column | Type | Constraints | Description |
|--------|------|-------------|-------------|
| id | UUID | PK | Region request identifier |
| latitude | DOUBLE PRECISION | NOT NULL | Center latitude |
| longitude | DOUBLE PRECISION | NOT NULL | Center longitude |
| size_meters | DOUBLE PRECISION | NOT NULL | Square region side length |
| zoom_level | INT | NOT NULL | Zoom level for tiles |
| status | VARCHAR(20) | NOT NULL | pending / processing / completed / failed |
| stitch_tiles | BOOLEAN | NOT NULL, DEFAULT false | Whether to produce stitched image |
| csv_file_path | VARCHAR(500) | | Path to tile manifest CSV |
| summary_file_path | VARCHAR(500) | | Path to summary text |
| tiles_downloaded | INT | DEFAULT 0 | Count of newly downloaded tiles |
| tiles_reused | INT | DEFAULT 0 | Count of cache-hit tiles |
| created_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |
| updated_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |

**Indexes**:
- `idx_regions_status` (status)

### routes

Defines route paths with configuration for map tile generation.

| Column | Type | Constraints | Description |
|--------|------|-------------|-------------|
| id | UUID | PK | Route identifier |
| name | VARCHAR(200) | NOT NULL | Human-readable name |
| description | TEXT | | Optional description |
| region_size_meters | DOUBLE PRECISION | NOT NULL | Size of region per point |
| zoom_level | INT | NOT NULL | Zoom level for regions |
| total_distance_meters | DOUBLE PRECISION | NOT NULL | Total route length |
| total_points | INT | NOT NULL | Total point count (original + interpolated) |
| request_maps | BOOLEAN | NOT NULL, DEFAULT false | Whether to generate map tiles |
| maps_ready | BOOLEAN | NOT NULL, DEFAULT false | Whether map generation is complete |
| create_tiles_zip | BOOLEAN | NOT NULL, DEFAULT false | Whether to produce ZIP archive |
| tiles_zip_path | VARCHAR(500) | | Path to output ZIP |
| csv_file_path | VARCHAR(500) | | Route-level CSV |
| summary_file_path | VARCHAR(500) | | Route-level summary |
| stitched_image_path | VARCHAR(500) | | Route-level stitched image |
| created_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |
| updated_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |

### route_points

Stores all points along a route (both original waypoints and interpolated intermediate points).

| Column | Type | Constraints | Description |
|--------|------|-------------|-------------|
| id | UUID | PK | Point identifier |
| route_id | UUID | FK → routes.id, CASCADE | Parent route |
| sequence_number | INT | NOT NULL, UNIQUE(route_id, seq) | Order along route |
| latitude | DOUBLE PRECISION | NOT NULL | Point latitude |
| longitude | DOUBLE PRECISION | NOT NULL | Point longitude |
| point_type | VARCHAR(20) | NOT NULL | "original" or "intermediate" |
| segment_index | INT | NOT NULL | Which segment (between original points) |
| distance_from_previous | DOUBLE PRECISION | | Meters from previous point |
| created_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |

**Indexes**:
- `idx_route_points_route` (route_id, sequence_number)
- `idx_route_points_coords` (latitude, longitude)

### route_regions

Junction table linking routes to their generated region requests, with geofence metadata.

| Column | Type | Constraints | Description |
|--------|------|-------------|-------------|
| route_id | UUID | FK → routes.id, CASCADE, PK | |
| region_id | UUID | FK → regions.id, CASCADE, PK | |
| is_geofence | BOOLEAN | NOT NULL, DEFAULT false | Whether point is inside a geofence |
| geofence_polygon_index | INTEGER | | Which polygon (0-based) the point is in |
| created_at | TIMESTAMP | NOT NULL, DEFAULT NOW | |

**Indexes**:
- `idx_route_regions_route` (route_id)
- `idx_route_regions_region` (region_id)

## Migration Strategy

- **Tool**: DbUp (embedded SQL scripts)
- **Execution**: Automatic on application startup (`DatabaseMigrator.Migrate()`)
- **Naming**: `NNN_DescriptiveName.sql` (sequential numbering)
- **Storage**: Embedded resources in `SatelliteProvider.DataAccess` assembly
- **Tracking**: DbUp's internal `schemaversions` table records which scripts have run
- **Rollback**: Not supported — forward-only migrations

## Migration History

| # | Migration | Purpose |
|---|-----------|---------|
| 001 | CreateTilesTable | Base tiles table |
| 002 | CreateRegionsTable | Region request tracking |
| 003 | CreateIndexes | Performance indexes |
| 004 | AddVersionColumn | Year-based tile versioning + dedup |
| 005 | CreateRoutesTables | Routes, route_points, route_regions |
| 006 | AddStitchTilesToRegions | Stitch flag on regions |
| 007 | AddRouteMapFields | request_maps, maps_ready, file paths on routes |
| 008 | AddGeofenceFlagToRouteRegions | is_geofence flag |
| 009 | AddGeofencePolygonIndex | Polygon index tracking |
| 010 | AddTilesZipToRoutes | ZIP generation fields |
| 011 | AddTileCoordinates | Slippy map X/Y + rename zoom_level → tile_zoom |
| 012 | DropTileVersionConstraint | Drops legacy 5-col `(…, version)` unique index; replaces with 4-col `idx_tiles_unique_location` (preparation for AZ-484) |
| 013 | AddTileSourceAndCapturedAt | AZ-484: adds `source` (default `'google_maps'`) + `captured_at` columns; backfills both for pre-existing rows; replaces 4-col unique with 5-col `idx_tiles_unique_location_source`. Transactional; idempotent against partial replays |