639 lines
17 KiB
Markdown
639 lines
17 KiB
Markdown
---
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layout: default
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title: Metric aggregations
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parent: Aggregations
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nav_order: 2
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permalink: /aggregations/metric-agg/
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redirect_from:
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- /opensearch/metric-agg/
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---
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# Metric aggregations
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Metric aggregations let you perform simple calculations such as finding the minimum, maximum, and average values of a field.
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## Types of metric aggregations
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Metric aggregations are of two types: single-value metric aggregations and multi-value metric aggregations.
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### Single-value metric aggregations
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Single-value metric aggregations return a single metric. For example, `sum`, `min`, `max`, `avg`, `cardinality`, and `value_count`.
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### Multi-value metric aggregations
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Multi-value metric aggregations return more than one metric. For example, `stats`, `extended_stats`, `matrix_stats`, `percentile`, `percentile_ranks`, `geo_bound`, `top_hits`, and `scripted_metric`.
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## sum, min, max, avg
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The `sum`, `min`, `max`, and `avg` metrics are single-value metric aggregations that return the sum, minimum, maximum, and average values of a field, respectively.
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The following example calculates the total sum of the `taxful_total_price` field:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"sum_taxful_total_price": {
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"sum": {
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"field": "taxful_total_price"
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"sum_taxful_total_price" : {
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"value" : 350884.12890625
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}
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}
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}
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```
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In a similar fashion, you can find the minimum, maximum, and average values of a field.
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## cardinality
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The `cardinality` metric is a single-value metric aggregation that counts the number of unique or distinct values of a field.
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The following example finds the number of unique products in an eCommerce store:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"unique_products": {
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"cardinality": {
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"field": "products.product_id"
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"unique_products" : {
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"value" : 7033
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}
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}
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}
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```
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Cardinality count is approximate.
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If you have tens of thousands of products in your hypothetical store, an accurate cardinality calculation requires loading all the values into a hash set and returning its size. This approach doesn't scale well; it requires huge amounts of memory and can cause high latencies.
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You can control the trade-off between memory and accuracy with the `precision_threshold` setting. This setting defines the threshold below which counts are expected to be close to accurate. Above this value, counts might become a bit less accurate. The default value of `precision_threshold` is 3,000. The maximum supported value is 40,000.
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"unique_products": {
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"cardinality": {
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"field": "products.product_id",
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"precision_threshold": 10000
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}
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}
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}
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}
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```
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## value_count
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The `value_count` metric is a single-value metric aggregation that calculates the number of values that an aggregation is based on.
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For example, you can use the `value_count` metric with the `avg` metric to find how many numbers the aggregation uses to calculate an average value.
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"number_of_values": {
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"value_count": {
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"field": "taxful_total_price"
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"number_of_values" : {
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"value" : 4675
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}
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}
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}
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```
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## stats, extended_stats, matrix_stats
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The `stats` metric is a multi-value metric aggregation that returns all basic metrics such as `min`, `max`, `sum`, `avg`, and `value_count` in one aggregation query.
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The following example returns the basic stats for the `taxful_total_price` field:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"stats_taxful_total_price": {
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"stats": {
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"field": "taxful_total_price"
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"stats_taxful_total_price" : {
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"count" : 4675,
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"min" : 6.98828125,
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"max" : 2250.0,
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"avg" : 75.05542864304813,
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"sum" : 350884.12890625
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}
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}
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}
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```
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The `extended_stats` aggregation is an extended version of the `stats` aggregation. Apart from including basic stats, `extended_stats` also returns stats such as `sum_of_squares`, `variance`, and `std_deviation`.
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"extended_stats_taxful_total_price": {
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"extended_stats": {
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"field": "taxful_total_price"
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"extended_stats_taxful_total_price" : {
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"count" : 4675,
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"min" : 6.98828125,
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"max" : 2250.0,
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"avg" : 75.05542864304813,
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"sum" : 350884.12890625,
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"sum_of_squares" : 3.9367749294174194E7,
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"variance" : 2787.59157113862,
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"variance_population" : 2787.59157113862,
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"variance_sampling" : 2788.187974983536,
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"std_deviation" : 52.79764740155209,
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"std_deviation_population" : 52.79764740155209,
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"std_deviation_sampling" : 52.80329511482722,
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"std_deviation_bounds" : {
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"upper" : 180.6507234461523,
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"lower" : -30.53986616005605,
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"upper_population" : 180.6507234461523,
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"lower_population" : -30.53986616005605,
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"upper_sampling" : 180.66201887270256,
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"lower_sampling" : -30.551161586606312
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}
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}
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}
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}
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```
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The `std_deviation_bounds` object provides a visual variance of the data with an interval of plus/minus two standard deviations from the mean.
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To set the standard deviation to a different value, say 3, set `sigma` to 3:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"extended_stats_taxful_total_price": {
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"extended_stats": {
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"field": "taxful_total_price",
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"sigma": 3
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}
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}
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}
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}
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```
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The `matrix_stats` aggregation generates advanced stats for multiple fields in a matrix form.
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The following example returns advanced stats in a matrix form for the `taxful_total_price` and `products.base_price` fields:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"matrix_stats_taxful_total_price": {
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"matrix_stats": {
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"fields": ["taxful_total_price", "products.base_price"]
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"matrix_stats_taxful_total_price" : {
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"doc_count" : 4675,
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"fields" : [
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{
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"name" : "products.base_price",
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"count" : 4675,
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"mean" : 34.994239430147196,
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"variance" : 360.5035285833703,
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"skewness" : 5.530161335032702,
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"kurtosis" : 131.16306324042148,
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"covariance" : {
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"products.base_price" : 360.5035285833703,
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"taxful_total_price" : 846.6489362233166
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},
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"correlation" : {
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"products.base_price" : 1.0,
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"taxful_total_price" : 0.8444765264325268
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}
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},
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{
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"name" : "taxful_total_price",
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"count" : 4675,
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"mean" : 75.05542864304839,
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"variance" : 2788.1879749835402,
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"skewness" : 15.812149139924037,
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"kurtosis" : 619.1235507385902,
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"covariance" : {
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"products.base_price" : 846.6489362233166,
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"taxful_total_price" : 2788.1879749835402
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},
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"correlation" : {
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"products.base_price" : 0.8444765264325268,
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"taxful_total_price" : 1.0
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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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Statistic | Description
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:--- | :---
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`count` | The number of samples measured.
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`mean` | The average value of the field measured from the sample.
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`variance` | How far the values of the field measured are spread out from its mean value. The larger the variance, the more it's spread from its mean value.
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`skewness` | An asymmetric measure of the distribution of the field's values around the mean.
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`kurtosis` | A measure of the tail heaviness of a distribution. As the tail becomes lighter, kurtosis decreases. As the tail becomes heavier, kurtosis increases. To learn about kurtosis, see [Wikipedia](https://en.wikipedia.org/wiki/Kurtosis).
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`covariance` | A measure of the joint variability between two fields. A positive value means their values move in the same direction and vice versa.
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`correlation` | A measure of the strength of the relationship between two fields. The valid values are between [-1, 1]. A value of -1 means that the value is negatively correlated and a value of 1 means that it's positively correlated. A value of 0 means that there's no identifiable relationship between them.
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## percentile, percentile_ranks
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Percentile is the percentage of the data that's at or below a certain threshold value.
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The `percentile` metric is a multi-value metric aggregation that lets you find outliers in your data or figure out the distribution of your data.
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Like the `cardinality` metric, the `percentile` metric is also approximate.
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The following example calculates the percentile in relation to the `taxful_total_price` field:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"percentile_taxful_total_price": {
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"percentiles": {
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"field": "taxful_total_price"
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"percentile_taxful_total_price" : {
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"values" : {
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"1.0" : 21.984375,
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"5.0" : 27.984375,
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"25.0" : 44.96875,
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"50.0" : 64.22061688311689,
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"75.0" : 93.0,
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"95.0" : 156.0,
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"99.0" : 222.0
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}
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}
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}
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}
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```
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Percentile rank is the percentile of values at or below a threshold grouped by a specified value. For example, if a value is greater than or equal to 80% of the values, it has a percentile rank of 80.
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"percentile_rank_taxful_total_price": {
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"percentile_ranks": {
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"field": "taxful_total_price",
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"values": [
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10,
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15
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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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#### Example response
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```json
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...
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"aggregations" : {
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"percentile_rank_taxful_total_price" : {
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"values" : {
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"10.0" : 0.055096056411283456,
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"15.0" : 0.0830092961834656
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}
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}
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}
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}
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```
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## geo_bound
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The `geo_bound` metric is a multi-value metric aggregation that calculates the bounding box in terms of latitude and longitude around a `geo_point` field.
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The following example returns the `geo_bound` metrics for the `geoip.location` field:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"geo": {
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"geo_bounds": {
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"field": "geoip.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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#### Example response
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```json
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"aggregations" : {
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"geo" : {
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"bounds" : {
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"top_left" : {
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"lat" : 52.49999997206032,
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"lon" : -118.20000001229346
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},
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"bottom_right" : {
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"lat" : 4.599999985657632,
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"lon" : 55.299999956041574
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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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## top_hits
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The `top_hits` metric is a multi-value metric aggregation that ranks the matching documents based on a relevance score for the field that's being aggregated.
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You can specify the following options:
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- `from`: The starting position of the hit.
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- `size`: The maximum size of hits to return. The default value is 3.
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- `sort`: How the matching hits are sorted. By default, the hits are sorted by the relevance score of the aggregation query.
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The following example returns the top 5 products in your eCommerce data:
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```json
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GET opensearch_dashboards_sample_data_ecommerce/_search
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{
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"size": 0,
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"aggs": {
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"top_hits_products": {
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"top_hits": {
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"size": 5
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}
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}
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}
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}
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```
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#### Example response
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```json
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...
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"aggregations" : {
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"top_hits_products" : {
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"hits" : {
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"total" : {
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"value" : 4675,
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"relation" : "eq"
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},
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"max_score" : 1.0,
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"hits" : [
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{
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"_index" : "opensearch_dashboards_sample_data_ecommerce",
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"_type" : "_doc",
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"_id" : "glMlwXcBQVLeQPrkHPtI",
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"_score" : 1.0,
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"_source" : {
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"category" : [
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"Women's Accessories",
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"Women's Clothing"
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],
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"currency" : "EUR",
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"customer_first_name" : "rania",
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"customer_full_name" : "rania Evans",
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"customer_gender" : "FEMALE",
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"customer_id" : 24,
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"customer_last_name" : "Evans",
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"customer_phone" : "",
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"day_of_week" : "Sunday",
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"day_of_week_i" : 6,
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"email" : "rania@evans-family.zzz",
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"manufacturer" : [
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"Tigress Enterprises"
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],
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"order_date" : "2021-02-28T14:16:48+00:00",
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"order_id" : 583581,
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"products" : [
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{
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"base_price" : 10.99,
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"discount_percentage" : 0,
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"quantity" : 1,
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"manufacturer" : "Tigress Enterprises",
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"tax_amount" : 0,
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"product_id" : 19024,
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"category" : "Women's Accessories",
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"sku" : "ZO0082400824",
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"taxless_price" : 10.99,
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"unit_discount_amount" : 0,
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"min_price" : 5.17,
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"_id" : "sold_product_583581_19024",
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"discount_amount" : 0,
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"created_on" : "2016-12-25T14:16:48+00:00",
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"product_name" : "Snood - white/grey/peach",
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"price" : 10.99,
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"taxful_price" : 10.99,
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"base_unit_price" : 10.99
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},
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{
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"base_price" : 32.99,
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"discount_percentage" : 0,
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"quantity" : 1,
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"manufacturer" : "Tigress Enterprises",
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"tax_amount" : 0,
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"product_id" : 19260,
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"category" : "Women's Clothing",
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"sku" : "ZO0071900719",
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"taxless_price" : 32.99,
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"unit_discount_amount" : 0,
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"min_price" : 17.15,
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"_id" : "sold_product_583581_19260",
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"discount_amount" : 0,
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"created_on" : "2016-12-25T14:16:48+00:00",
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"product_name" : "Cardigan - grey",
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"price" : 32.99,
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"taxful_price" : 32.99,
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"base_unit_price" : 32.99
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}
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],
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"sku" : [
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"ZO0082400824",
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"ZO0071900719"
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],
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"taxful_total_price" : 43.98,
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"taxless_total_price" : 43.98,
|
|
"total_quantity" : 2,
|
|
"total_unique_products" : 2,
|
|
"type" : "order",
|
|
"user" : "rani",
|
|
"geoip" : {
|
|
"country_iso_code" : "EG",
|
|
"location" : {
|
|
"lon" : 31.3,
|
|
"lat" : 30.1
|
|
},
|
|
"region_name" : "Cairo Governorate",
|
|
"continent_name" : "Africa",
|
|
"city_name" : "Cairo"
|
|
},
|
|
"event" : {
|
|
"dataset" : "sample_ecommerce"
|
|
}
|
|
}
|
|
...
|
|
}
|
|
]
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
## scripted_metric
|
|
|
|
The `scripted_metric` metric is a multi-value metric aggregation that returns metrics calculated from a specified script.
|
|
|
|
A script has four stages: the initial stage, the map stage, the combine stage, and the reduce stage.
|
|
|
|
* `init_script`: (OPTIONAL) Sets the initial state and executes before any collection of documents.
|
|
* `map_script`: Checks the value of the `type` field and executes the aggregation on the collected documents.
|
|
* `combine_script`: Aggregates the state returned from every shard. The aggregated value is returned to the coordinating node.
|
|
* `reduce_script`: Provides access to the variable states; this variable combines the results from the `combine_script` on each shard into an array.
|
|
|
|
The following example aggregates the different HTTP response types in web log data:
|
|
|
|
```json
|
|
GET opensearch_dashboards_sample_data_logs/_search
|
|
{
|
|
"size": 0,
|
|
"aggregations": {
|
|
"responses.counts": {
|
|
"scripted_metric": {
|
|
"init_script": "state.responses = ['error':0L,'success':0L,'other':0L]",
|
|
"map_script": """
|
|
def code = doc['response.keyword'].value;
|
|
if (code.startsWith('5') || code.startsWith('4')) {
|
|
state.responses.error += 1 ;
|
|
} else if(code.startsWith('2')) {
|
|
state.responses.success += 1;
|
|
} else {
|
|
state.responses.other += 1;
|
|
}
|
|
""",
|
|
"combine_script": "state.responses",
|
|
"reduce_script": """
|
|
def counts = ['error': 0L, 'success': 0L, 'other': 0L];
|
|
for (responses in states) {
|
|
counts.error += responses['error'];
|
|
counts.success += responses['success'];
|
|
counts.other += responses['other'];
|
|
}
|
|
return counts;
|
|
"""
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
#### Example response
|
|
|
|
```json
|
|
...
|
|
"aggregations" : {
|
|
"responses.counts" : {
|
|
"value" : {
|
|
"other" : 0,
|
|
"success" : 12832,
|
|
"error" : 1242
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|