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* Added documentation for cartesian-bounds aggregation * Fixed rounding errors in docs tests
229 lines
6.5 KiB
Text
229 lines
6.5 KiB
Text
[[search-aggregations-metrics-cartesian-centroid-aggregation]]
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=== Cartesian-centroid aggregation
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++++
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<titleabbrev>Cartesian-centroid</titleabbrev>
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++++
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A metric aggregation that computes the weighted {wikipedia}/Centroid[centroid] from all coordinate values for point and shape fields.
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Example:
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[source,console]
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--------------------------------------------------
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PUT /museums
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{
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"mappings": {
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"properties": {
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"location": {
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"type": "point"
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}
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}
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}
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}
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POST /museums/_bulk?refresh
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{"index":{"_id":1}}
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{"location": "POINT (491.2350 5237.4081)", "city": "Amsterdam", "name": "NEMO Science Museum"}
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{"index":{"_id":2}}
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{"location": "POINT (490.1618 5236.9219)", "city": "Amsterdam", "name": "Museum Het Rembrandthuis"}
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{"index":{"_id":3}}
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{"location": "POINT (491.4722 5237.1667)", "city": "Amsterdam", "name": "Nederlands Scheepvaartmuseum"}
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{"index":{"_id":4}}
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{"location": "POINT (440.5200 5122.2900)", "city": "Antwerp", "name": "Letterenhuis"}
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{"index":{"_id":5}}
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{"location": "POINT (233.6389 4886.1111)", "city": "Paris", "name": "Musée du Louvre"}
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{"index":{"_id":6}}
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{"location": "POINT (232.7000 4886.0000)", "city": "Paris", "name": "Musée d'Orsay"}
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POST /museums/_search?size=0
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{
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"aggs": {
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"centroid": {
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"cartesian_centroid": {
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"field": "location" <1>
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}
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}
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}
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}
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--------------------------------------------------
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<1> The `cartesian_centroid` aggregation specifies the field to use for computing the centroid, which must be a <<point>> or a <<shape>> type.
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The above aggregation demonstrates how one would compute the centroid of the location field for all museums' documents.
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The response for the above aggregation:
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[source,console-result]
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--------------------------------------------------
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{
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...
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"aggregations": {
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"centroid": {
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"location": {
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"x": 396.6213124593099,
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"y": 5100.982991536458
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},
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"count": 6
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}
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}
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}
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--------------------------------------------------
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// TESTRESPONSE[s/\.\.\./"took": $body.took,"_shards": $body._shards,"hits":$body.hits,"timed_out":false,/]
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The `cartesian_centroid` aggregation is more interesting when combined as a sub-aggregation to other bucket aggregations.
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Example:
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[source,console]
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--------------------------------------------------
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POST /museums/_search?size=0
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{
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"aggs": {
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"cities": {
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"terms": { "field": "city.keyword" },
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"aggs": {
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"centroid": {
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"cartesian_centroid": { "field": "location" }
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}
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}
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}
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}
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}
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--------------------------------------------------
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// TEST[continued]
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The above example uses `cartesian_centroid` as a sub-aggregation to a
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<<search-aggregations-bucket-terms-aggregation, terms>> bucket aggregation for finding the central location for museums in each city.
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The response for the above aggregation:
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[source,console-result]
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--------------------------------------------------
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{
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...
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"aggregations": {
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"cities": {
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"sum_other_doc_count": 0,
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"doc_count_error_upper_bound": 0,
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"buckets": [
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{
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"key": "Amsterdam",
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"doc_count": 3,
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"centroid": {
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"location": {
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"x": 490.9563293457031,
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"y": 5237.16552734375
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},
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"count": 3
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}
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},
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{
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"key": "Paris",
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"doc_count": 2,
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"centroid": {
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"location": {
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"x": 233.16944885253906,
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"y": 4886.0556640625
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},
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"count": 2
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}
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},
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{
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"key": "Antwerp",
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"doc_count": 1,
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"centroid": {
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"location": {
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"x": 440.5199890136719,
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"y": 5122.2900390625
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},
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"count": 1
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}
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}
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]
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}
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}
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}
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--------------------------------------------------
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// TESTRESPONSE[s/\.\.\./"took": $body.took,"_shards": $body._shards,"hits":$body.hits,"timed_out":false,/]
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[discrete]
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[role="xpack"]
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[[cartesian-centroid-aggregation-geo-shape]]
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==== Cartesian Centroid Aggregation on `shape` fields
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The centroid metric for shapes is more nuanced than for points.
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The centroid of a specific aggregation bucket containing shapes is the centroid of the highest-dimensionality shape type in the bucket.
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For example, if a bucket contains shapes consisting of polygons and lines, then the lines do not contribute to the centroid metric.
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Each type of shape's centroid is calculated differently.
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Envelopes and circles ingested via the <<ingest-circle-processor>> are treated as polygons.
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|===
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|Geometry Type | Centroid Calculation
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|[Multi]Point
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|equally weighted average of all the coordinates
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|[Multi]LineString
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|a weighted average of all the centroids of each segment, where the weight of each segment is its length in the same units as the coordinates
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|[Multi]Polygon
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|a weighted average of all the centroids of all the triangles of a polygon where the triangles are formed by every two consecutive vertices and the starting-point.
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holes have negative weights. weights represent the area of the triangle is calculated in the square of the units of the coordinates
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|GeometryCollection
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|The centroid of all the underlying geometries with the highest dimension. If Polygons and Lines and/or Points, then lines and/or points are ignored.
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If Lines and Points, then points are ignored
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|===
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Example:
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[source,console]
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--------------------------------------------------
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PUT /places
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{
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"mappings": {
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"properties": {
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"geometry": {
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"type": "shape"
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}
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}
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}
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}
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POST /places/_bulk?refresh
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{"index":{"_id":1}}
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{"name": "NEMO Science Museum", "geometry": "POINT(491.2350 5237.4081)" }
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{"index":{"_id":2}}
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{"name": "Sportpark De Weeren", "geometry": { "type": "Polygon", "coordinates": [ [ [ 496.5305328369141, 5239.347642069457 ], [ 496.6979026794433, 5239.1721758934835 ], [ 496.9425201416015, 5239.238958618537 ], [ 496.7944622039794, 5239.420969150824 ], [ 496.5305328369141, 5239.347642069457 ] ] ] } }
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POST /places/_search?size=0
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{
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"aggs": {
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"centroid": {
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"cartesian_centroid": {
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"field": "geometry"
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}
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}
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}
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}
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--------------------------------------------------
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// TEST
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[source,console-result]
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--------------------------------------------------
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{
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...
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"aggregations": {
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"centroid": {
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"location": {
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"x": 496.74041748046875,
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"y": 5239.29638671875
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},
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"count": 2
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}
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}
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}
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--------------------------------------------------
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// TESTRESPONSE[s/\.\.\./"took": $body.took,"_shards": $body._shards,"hits":$body.hits,"timed_out":false,/]
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