druid/docs/content/querying/topnmetricspec.md

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TopNMetricSpec

The topN metric spec specifies how topN values should be sorted.

Numeric TopNMetricSpec

The simplest metric specification is a String value indicating the metric to sort topN results by. They are included in a topN query with:

"metric": "<metric_name>"

The metric field can also be given as a JSON object. The grammar for dimension values sorted by numeric value is shown below:

"metric": {
    "type": "numeric",
    "metric": "<metric_name>"
}
property description required?
type this indicates a numeric sort yes
metric the actual metric field in which results will be sorted by yes

Lexicographic TopNMetricSpec

The grammar for dimension values sorted lexicographically is as follows:

"metric": {
    "type": "lexicographic",
    "previousStop": "<previousStop_value>"
}
property description required?
type this indicates a lexicographic sort yes
previousStop the starting point of the lexicographic sort. For example, if a previousStop value is 'b', all values before 'b' are discarded. This field can be used to paginate through all the dimension values. no

AlphaNumeric TopNMetricSpec

Sort dimension values in alpha-numeric order, i.e treating numbers differently from other characters in sorting the values. See http://www.davekoelle.com/alphanum.html for details on how the algorithm works.

"metric": {
    "type": "alphaNumeric",
    "previousStop": "<previousStop_value>"
}
property description required?
type this indicates an alpha-numeric sort yes
previousStop the starting point of the alpha-numeric sort. For example, if a previousStop value is 'b', all values before 'b' are discarded. This field can be used to paginate through all the dimension values. no

Inverted TopNMetricSpec

Sort dimension values in inverted order, i.e inverts the order of the delegate metric spec. It can be used to sort the values in descending order.

"metric": {
    "type": "inverted",
    "metric": <delegate_top_n_metric_spec>
}
property description required?
type this indicates an inverted sort yes
metric the delegate metric spec. yes