mirror of https://github.com/apache/druid.git
85 lines
2.4 KiB
Markdown
85 lines
2.4 KiB
Markdown
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---
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layout: doc_page
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---
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# Timestamp Min/Max aggregators
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To use this extension, make sure to [include](../../operations/including-extensions.html) `druid-time-min-max`.
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These aggregators enable more precise calculation of min and max time of given events than `__time` column whose granularity is sparse, the same as query granularity.
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To use this feature, a "timeMin" or "timeMax" aggregator must be included at indexing time.
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They can apply to any columns that can be converted to timestamp, which include Long, DateTime, Timestamp, and String types.
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For example, when a data set consists of timestamp, dimension, and metric value like followings.
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```
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2015-07-28T01:00:00.000Z A 1
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2015-07-28T02:00:00.000Z A 1
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2015-07-28T03:00:00.000Z A 1
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2015-07-28T04:00:00.000Z B 1
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2015-07-28T05:00:00.000Z A 1
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2015-07-28T06:00:00.000Z B 1
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2015-07-29T01:00:00.000Z C 1
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2015-07-29T02:00:00.000Z C 1
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2015-07-29T03:00:00.000Z A 1
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2015-07-29T04:00:00.000Z A 1
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```
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At ingestion time, timeMin and timeMax aggregator can be included as other aggregators.
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```json
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{
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"type": "timeMin",
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"name": "tmin",
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"fieldName": "<field_name, typically column specified in timestamp spec>"
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}
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```
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```json
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{
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"type": "timeMax",
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"name": "tmax",
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"fieldName": "<field_name, typically column specified in timestamp spec>"
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}
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```
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`name` is output name of aggregator and can be any string. `fieldName` is typically column specified in timestamp spec but can be any column that can be converted to timestamp.
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To query for results, the same aggregators "timeMin" and "timeMax" is used.
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```json
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{
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"queryType": "groupBy",
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"dataSource": "timeMinMax",
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"granularity": "DAY",
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"dimensions": ["product"],
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"aggregations": [
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{
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"type": "count",
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"name": "count"
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}
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{
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"type": "timeMin",
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"name": "<output_name of timeMin>",
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"fieldName": "tmin"
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},
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{
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"type": "timeMax",
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"name": "<output_name of timeMax>",
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"fieldName": "tmax"
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}
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],
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"intervals": [
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"2010-01-01T00:00:00.000Z/2020-01-01T00:00:00.000Z"
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]
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}
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```
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Then, result has min and max of timestamp, which is finer than query granularity.
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```
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2015-07-28T00:00:00.000Z A 4 2015-07-28T01:00:00.000Z 2015-07-28T05:00:00.000Z
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2015-07-28T00:00:00.000Z B 2 2015-07-28T04:00:00.000Z 2015-07-28T06:00:00.000Z
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2015-07-29T00:00:00.000Z A 2 2015-07-29T03:00:00.000Z 2015-07-29T04:00:00.000Z
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2015-07-29T00:00:00.000Z C 2 2015-07-29T01:00:00.000Z 2015-07-29T02:00:00.000Z
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```
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