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Spatial filters

Apache Druid (incubating) supports filtering specially spatially indexed columns based on an origin and a bound.

Spatial indexing

In any of the data specs, there is the option of providing spatial dimensions. For example, for a JSON data spec, spatial dimensions can be specified as follows:

{
    "type": "hadoop",
    "dataSchema": {
        "dataSource": "DatasourceName",
        "parser": {
            "type": "string",
            "parseSpec": {
                "format": "json",
                "timestampSpec": {
                    "column": "timestamp",
                    "format": "auto"
                },
                "dimensionsSpec": {
                    "dimensions": [],
                    "spatialDimensions": [{
                        "dimName": "coordinates",
                        "dims": ["lat", "long"]
                    }]
                }
            }
        }
    }
}

Spatial filters

property	description	required?
dimName	The name of the spatial dimension. A spatial dimension may be constructed from multiple other dimensions or it may already exist as part of an event. If a spatial dimension already exists, it must be an array of coordinate values.	yes
dims	A list of dimension names that comprise a spatial dimension.	no

The grammar for a spatial filter is as follows:

"filter" : {
    "type": "spatial",
    "dimension": "spatialDim",
    "bound": {
        "type": "rectangular",
        "minCoords": [10.0, 20.0],
        "maxCoords": [30.0, 40.0]
    }
}

Bound types

rectangular

property	description	required?
minCoords	List of minimum dimension coordinates for coordinates [x, y, z, …]	yes
maxCoords	List of maximum dimension coordinates for coordinates [x, y, z, …]	yes

radius

property	description	required?
coords	Origin coordinates in the form [x, y, z, …]	yes
radius	The float radius value	yes

polygon

property	description	required?
abscissa	Horizontal coordinate for corners of the polygon	yes
ordinate	Vertical coordinate for corners of the polygon	yes