74 lines
2.2 KiB
Markdown
74 lines
2.2 KiB
Markdown
---
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layout: default
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title: Scripted metric
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parent: Metric aggregations
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grand_parent: Aggregations
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nav_order: 100
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redirect_from:
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- /query-dsl/aggregations/metric/scripted-metric/
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---
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# Scripted metric aggregations
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The `scripted_metric` metric is a multi-value metric aggregation that returns metrics calculated from a specified script.
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A script has four stages: the initial stage, the map stage, the combine stage, and the reduce stage.
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* `init_script`: (OPTIONAL) Sets the initial state and executes before any collection of documents.
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* `map_script`: Checks the value of the `type` field and executes the aggregation on the collected documents.
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* `combine_script`: Aggregates the state returned from every shard. The aggregated value is returned to the coordinating node.
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* `reduce_script`: Provides access to the variable states; this variable combines the results from the `combine_script` on each shard into an array.
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The following example aggregates the different HTTP response types in web log data:
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```json
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GET opensearch_dashboards_sample_data_logs/_search
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{
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"size": 0,
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"aggregations": {
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"responses.counts": {
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"scripted_metric": {
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"init_script": "state.responses = ['error':0L,'success':0L,'other':0L]",
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"map_script": """
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def code = doc['response.keyword'].value;
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if (code.startsWith('5') || code.startsWith('4')) {
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state.responses.error += 1 ;
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} else if(code.startsWith('2')) {
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state.responses.success += 1;
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} else {
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state.responses.other += 1;
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}
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""",
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"combine_script": "state.responses",
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"reduce_script": """
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def counts = ['error': 0L, 'success': 0L, 'other': 0L];
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for (responses in states) {
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counts.error += responses['error'];
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counts.success += responses['success'];
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counts.other += responses['other'];
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}
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return counts;
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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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{% include copy-curl.html %}
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#### Example response
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```json
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...
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"aggregations" : {
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"responses.counts" : {
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"value" : {
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"other" : 0,
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"success" : 12832,
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"error" : 1242
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}
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}
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}
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}
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```
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