Mapping a GeoShape field_ElasticSearch Cookbook-QQ阅读女生现言网

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Mapping a GeoShape field

An extension to the concept of point is the shape. ElasticSearch provides a type that facilitates the management of arbitrary polygons—the GeoShape.

You need a working ElasticSearch cluster with Spatial4J (V0.3) and JTS (v1.12) in the classpath to use this type.

To map a geo_shape type a user must explicitly provide some parameters:

tree (defaults to geohash): It's the name of the PrefixTree implementation; geohash for GeohashPrefixTree and quadtree for QuadPrefixTree.
precision: It's used instead of tree_levels to provide a more human value to be used in the tree level. The precision number can be followed by the unit, that is, 10 m, 10 km, 10 miles, and so on.
tree_levels: It's the maximum number of layers to be used in the PrefixTree.
distance_error_pct (defaults to 0,025% and max 0,5%): It sets the maximum error allowed in PrefixTree.

The customer_location mapping that we have seen in the previous recipe using geo_shape, will be:

"customer_location": {
    "type": "geo_shape",
    "tree": "quadtree",
    "precision": "1m"
},

When a shape is indexed or searched internally, a path tree is created and used.

A path tree is a list of terms that contains geographic information, computed to improve performance in evaluating geo calculus.

The path tree also depends on the shape type: point, linestring, polygon, multipoint, and multipolygon.