mirror of https://github.com/apache/druid.git
79 lines
2.3 KiB
Markdown
79 lines
2.3 KiB
Markdown
---
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layout: doc_page
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---
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TopNMetricSpec
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==================
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The topN metric spec specifies how topN values should be sorted.
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## Numeric TopNMetricSpec
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The simplest metric specification is a String value indicating the metric to sort topN results by. They are included in a topN query with:
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```json
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"metric": "<metric_name>"
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```
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The metric field can also be given as a JSON object. The grammar for dimension values sorted by numeric value is shown below:
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```json
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"metric": {
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"type": "numeric",
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"metric": "<metric_name>"
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}
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```
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|property|description|required?|
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|--------|-----------|---------|
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|type|this indicates a numeric sort|yes|
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|metric|the actual metric field in which results will be sorted by|yes|
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## Lexicographic TopNMetricSpec
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The grammar for dimension values sorted lexicographically is as follows:
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```json
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"metric": {
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"type": "lexicographic",
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"previousStop": "<previousStop_value>"
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}
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```
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|property|description|required?|
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|--------|-----------|---------|
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|type|this indicates a lexicographic sort|yes|
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|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|
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## AlphaNumeric TopNMetricSpec
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Sort dimension values in alpha-numeric order, i.e treating numbers differently from other characters in sorting the values.
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The algorithm is based on [https://github.com/amjjd/java-alphanum](https://github.com/amjjd/java-alphanum).
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```json
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"metric": {
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"type": "alphaNumeric",
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"previousStop": "<previousStop_value>"
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}
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```
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|property|description|required?|
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|--------|-----------|---------|
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|type|this indicates an alpha-numeric sort|yes|
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|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|
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## Inverted TopNMetricSpec
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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 ascending order.
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```json
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"metric": {
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"type": "inverted",
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"metric": <delegate_top_n_metric_spec>
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}
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```
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|property|description|required?|
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|--------|-----------|---------|
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|type|this indicates an inverted sort|yes|
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|metric|the delegate metric spec. |yes|
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