65 lines
1.6 KiB
Plaintext
65 lines
1.6 KiB
Plaintext
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[[geohash-prefix]]
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=== `geohash_prefix`
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Geohashes are a form of lat/lon encoding which divides the earth up into
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a grid. Each cell in this grid is represented by a geohash string. Each
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cell in turn can be further subdivided into smaller cells which are
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represented by a longer string. So the longer the geohash, the smaller
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(and thus more accurate) the cell is.
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While the <<geohash,`geohash`>> option enables indexing the geohash that
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corresponds to the lat/lon point, at the specified
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<<geohash-precision,precision>>, the `geohash_prefix` option will also
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index all the enclosing cells as well.
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For instance, a geohash of `drm3btev3e86` will index all of the following
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terms: [ `d`, `dr`, `drm`, `drm3`, `drm3b`, `drm3bt`, `drm3bte`, `drm3btev`,
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`drm3btev3`, `drm3btev3e`, `drm3btev3e8`, `drm3btev3e86` ].
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The geohash prefixes can be used with the
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<<query-dsl-geohash-cell-query,`geohash_cell` query>> to find points within a
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particular geohash, or its neighbours:
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[source,js]
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--------------------------------------------------
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PUT my_index
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{
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"mappings": {
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"my_type": {
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"properties": {
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"location": {
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"type": "geo_point",
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"geohash_prefix": true,
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"geohash_precision": 6
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}
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}
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}
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}
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}
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PUT my_index/my_type/1
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{
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"location": {
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"lat": 41.12,
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"lon": -71.34
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}
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}
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GET my_index/_search?fielddata_fields=location.geohash
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{
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"query": {
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"geohash_cell": {
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"location": {
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"lat": 41.02,
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"lon": -71.48
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},
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"precision": 4, <1>
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"neighbors": true <1>
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}
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}
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}
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--------------------------------------------------
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// AUTOSENSE
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