Spatial filters

Apache Druid 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:

  1. {
  2.     "type": "hadoop",
  3.     "dataSchema": {
  4.         "dataSource": "DatasourceName",
  5.         "parser": {
  6.             "type": "string",
  7.             "parseSpec": {
  8.                 "format": "json",
  9.                 "timestampSpec": {
  10.                     "column": "timestamp",
  11.                     "format": "auto"
  12.                 },
  13.                 "dimensionsSpec": {
  14.                     "dimensions": [],
  15.                     "spatialDimensions": [{
  16.                         "dimName": "coordinates",
  17.                         "dims": ["lat", "long"]
  18.                     }]
  19.                 }
  20.             }
  21.         }
  22.     }
  23. }

Spatial filters

propertydescriptionrequired?
dimNameThe 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
dimsA list of dimension names that comprise a spatial dimension.no

The grammar for a spatial filter is as follows:

  1. "filter" : {
  2.     "type": "spatial",
  3.     "dimension": "spatialDim",
  4.     "bound": {
  5.         "type": "rectangular",
  6.         "minCoords": [10.0, 20.0],
  7.         "maxCoords": [30.0, 40.0]
  8.     }
  9. }

Bound types

rectangular

propertydescriptionrequired?
minCoordsList of minimum dimension coordinates for coordinates [x, y, z, …]yes
maxCoordsList of maximum dimension coordinates for coordinates [x, y, z, …]yes

radius

propertydescriptionrequired?
coordsOrigin coordinates in the form [x, y, z, …]yes
radiusThe float radius valueyes

polygon

propertydescriptionrequired?
abscissaHorizontal coordinate for corners of the polygonyes
ordinateVertical coordinate for corners of the polygonyes