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122 lines
3.8 KiB
Markdown
122 lines
3.8 KiB
Markdown
---
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slug: /en/sql-reference/functions/time-window-functions
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sidebar_position: 175
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sidebar_label: Time Window
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---
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# Time Window Functions
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Time window functions return the inclusive lower and exclusive upper bound of the corresponding window. The functions for working with WindowView are listed below:
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## tumble
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A tumbling time window assigns records to non-overlapping, continuous windows with a fixed duration (`interval`).
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``` sql
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tumble(time_attr, interval [, timezone])
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```
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**Arguments**
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- `time_attr` - Date and time. [DateTime](../../sql-reference/data-types/datetime.md) data type.
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- `interval` - Window interval in [Interval](../../sql-reference/data-types/special-data-types/interval.md) data type.
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- `timezone` — [Timezone name](../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-timezone) (optional).
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**Returned values**
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- The inclusive lower and exclusive upper bound of the corresponding tumbling window.
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Type: `Tuple(DateTime, DateTime)`
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**Example**
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Query:
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``` sql
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SELECT tumble(now(), toIntervalDay('1'))
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```
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Result:
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``` text
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┌─tumble(now(), toIntervalDay('1'))─────────────┐
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│ ['2020-01-01 00:00:00','2020-01-02 00:00:00'] │
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└───────────────────────────────────────────────┘
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```
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## hop
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A hopping time window has a fixed duration (`window_interval`) and hops by a specified hop interval (`hop_interval`). If the `hop_interval` is smaller than the `window_interval`, hopping windows are overlapping. Thus, records can be assigned to multiple windows.
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``` sql
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hop(time_attr, hop_interval, window_interval [, timezone])
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```
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**Arguments**
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- `time_attr` - Date and time. [DateTime](../../sql-reference/data-types/datetime.md) data type.
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- `hop_interval` - Hop interval in [Interval](../../sql-reference/data-types/special-data-types/interval.md) data type. Should be a positive number.
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- `window_interval` - Window interval in [Interval](../../sql-reference/data-types/special-data-types/interval.md) data type. Should be a positive number.
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- `timezone` — [Timezone name](../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-timezone) (optional).
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**Returned values**
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- The inclusive lower and exclusive upper bound of the corresponding hopping window. Since one record can be assigned to multiple hop windows, the function only returns the bound of the **first** window when hop function is used **without** `WINDOW VIEW`.
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Type: `Tuple(DateTime, DateTime)`
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**Example**
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Query:
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``` sql
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SELECT hop(now(), INTERVAL '1' SECOND, INTERVAL '2' SECOND)
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```
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Result:
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``` text
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┌─hop(now(), toIntervalSecond('1'), toIntervalSecond('2'))──┐
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│ ('2020-01-14 16:58:22','2020-01-14 16:58:24') │
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└───────────────────────────────────────────────────────────┘
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```
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## tumbleStart
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Returns the inclusive lower bound of the corresponding tumbling window.
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``` sql
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tumbleStart(bounds_tuple);
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tumbleStart(time_attr, interval [, timezone]);
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```
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## tumbleEnd
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Returns the exclusive upper bound of the corresponding tumbling window.
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``` sql
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tumbleEnd(bounds_tuple);
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tumbleEnd(time_attr, interval [, timezone]);
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```
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## hopStart
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Returns the inclusive lower bound of the corresponding hopping window.
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``` sql
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hopStart(bounds_tuple);
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hopStart(time_attr, hop_interval, window_interval [, timezone]);
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```
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## hopEnd
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Returns the exclusive upper bound of the corresponding hopping window.
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``` sql
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hopEnd(bounds_tuple);
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hopEnd(time_attr, hop_interval, window_interval [, timezone]);
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```
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## Related content
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- Blog: [Working with time series data in ClickHouse](https://clickhouse.com/blog/working-with-time-series-data-and-functions-ClickHouse)
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