This is used to compute metrics based on values extracted from the fields of a document. Metrics are used in conjunction with buckets. The different metrics that are available are as follows:

• Count: The default metric in Kibana visualizations; returns the count of documents
• Average: Used to compute the average value (for a field) of all the documents in the bucket
• Sum: Used to compute the sum value (for a field) of all the documents in the bucket
• Median: Used to compute the median value (for a field) of all the documents in the bucket
• Min: Used to compute the minimum value (for a field) of all the documents in the bucket
• Max: Used to compute the maximum value (for a field) of all the documents in the bucket
• Standard deviation: Used to compute the standard deviation (for a field) of all the documents in the bucket
• Percentiles: Used to compute the number of percentile values
• Percentile ranks: For a set of percentiles, this is used to compute the corresponding values