> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-fix-nav-issues.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Documentation for time window functions

# 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](/reference/statements/create/view#window-view) are listed below:

{/*AUTOGENERATED_START*/}

<h2 id="hop">
  hop
</h2>

Introduced in: v21.12.0

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.

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.

**Syntax**

```sql theme={null}
hop(time_attr, hop_interval, window_interval[, timezone])
```

**Arguments**

* `time_attr` — Date and time. [`DateTime`](/reference/data-types/datetime)
* `hop_interval` — Positive Hop interval. [`Interval`](/reference/data-types/int-uint)
* `window_interval` — Positive Window interval. [`Interval`](/reference/data-types/int-uint)
* `timezone` — Optional. Timezone name. [`String`](/reference/data-types/string)

**Returned value**

Returns the inclusive lower and exclusive upper bound of the corresponding hopping window. [`Tuple(DateTime, DateTime)`](/reference/data-types/tuple)

**Examples**

**Hopping window**

```sql title=Query theme={null}
SELECT hop(now(), INTERVAL '1' DAY, INTERVAL '2' DAY)
```

```response title=Response theme={null}
('2024-07-03 00:00:00','2024-07-05 00:00:00')
```

<h2 id="hopEnd">
  hopEnd
</h2>

Introduced in: v22.1.0

Returns the 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`.

**Syntax**

```sql theme={null}
hopEnd(time_attr, hop_interval, window_interval[, timezone])
```

**Arguments**

* `time_attr` — Date and time. [`DateTime`](/reference/data-types/datetime)
* `hop_interval` — Positive Hop interval. [`Interval`](/reference/data-types/int-uint)
* `window_interval` — Positive Window interval. [`Interval`](/reference/data-types/int-uint)
* `timezone` — Optional. Timezone name. [`String`](/reference/data-types/string)

**Returned value**

Returns the exclusive upper bound of the corresponding hopping window. [`DateTime`](/reference/data-types/datetime)

**Examples**

**Hopping window end**

```sql title=Query theme={null}
SELECT hopEnd(now(), INTERVAL '1' DAY, INTERVAL '2' DAY)
```

```response title=Response theme={null}
2024-07-05 00:00:00
```

<h2 id="hopStart">
  hopStart
</h2>

Introduced in: v22.1.0

Returns the inclusive lower 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`.

**Syntax**

```sql theme={null}
hopStart(time_attr, hop_interval, window_interval[, timezone])
```

**Arguments**

* `time_attr` — Date and time. [`DateTime`](/reference/data-types/datetime)
* `hop_interval` — Positive Hop interval. [`Interval`](/reference/data-types/int-uint)
* `window_interval` — Positive Window interval. [`Interval`](/reference/data-types/int-uint)
* `timezone` — Optional. Timezone name. [`String`](/reference/data-types/string)

**Returned value**

Returns the inclusive lower bound of the corresponding hopping window. [`DateTime`](/reference/data-types/datetime)

**Examples**

**Hopping window start**

```sql title=Query theme={null}
SELECT hopStart(now(), INTERVAL '1' DAY, INTERVAL '2' DAY)
```

```response title=Response theme={null}
2024-07-03 00:00:00
```

<h2 id="tumble">
  tumble
</h2>

Introduced in: v21.12.0

A tumbling time window assigns records to non-overlapping, continuous windows with a fixed duration (`interval`).

**Syntax**

```sql theme={null}
tumble(time_attr, interval[, timezone])
```

**Arguments**

* `time_attr` — Date and time. [`DateTime`](/reference/data-types/datetime)
* `interval` — Window interval in Interval. [`Interval`](/reference/data-types/int-uint)
* `timezone` — Optional. Timezone name. [`String`](/reference/data-types/string)

**Returned value**

Returns the inclusive lower and exclusive upper bound of the corresponding tumbling window. [`Tuple(DateTime, DateTime)`](/reference/data-types/tuple)

**Examples**

**Tumbling window**

```sql title=Query theme={null}
SELECT tumble(now(), toIntervalDay('1'))
```

```response title=Response theme={null}
('2024-07-04 00:00:00','2024-07-05 00:00:00')
```

<h2 id="tumbleEnd">
  tumbleEnd
</h2>

Introduced in: v22.1.0

Returns the exclusive upper bound of the corresponding tumbling window.

**Syntax**

```sql theme={null}
tumbleEnd(time_attr, interval[, timezone])
```

**Arguments**

* `time_attr` — Date and time. [`DateTime`](/reference/data-types/datetime)
* `interval` — Window interval in Interval. [`Interval`](/reference/data-types/int-uint)
* `timezone` — Optional. Timezone name. [`String`](/reference/data-types/string)

**Returned value**

Returns the exclusive upper bound of the corresponding tumbling window. [`DateTime`](/reference/data-types/datetime)

**Examples**

**Tumbling window end**

```sql title=Query theme={null}
SELECT tumbleEnd(now(), toIntervalDay('1'))
```

```response title=Response theme={null}
2024-07-05 00:00:00
```

<h2 id="tumbleStart">
  tumbleStart
</h2>

Introduced in: v22.1.0

Returns the inclusive lower bound of the corresponding tumbling window.

**Syntax**

```sql theme={null}
tumbleStart(time_attr, interval[, timezone])
```

**Arguments**

* `time_attr` — Date and time. [`DateTime`](/reference/data-types/datetime)
* `interval` — Window interval in Interval. [`Interval`](/reference/data-types/int-uint)
* `timezone` — Optional. Timezone name. [`String`](/reference/data-types/string)

**Returned value**

Returns the inclusive lower bound of the corresponding tumbling window. [`DateTime`](/reference/data-types/datetime)

**Examples**

**Tumbling window start**

```sql title=Query theme={null}
SELECT tumbleStart(now(), toIntervalDay('1'))
```

```response title=Response theme={null}
2024-07-04 00:00:00
```

<h2 id="windowID">
  windowID
</h2>

Introduced in: v22.1.0

Returns the window identifier of the corresponding tumbling or hopping window.
This function can only be used with `WINDOW VIEW`.

**Syntax**

```sql theme={null}
windowID(time_attr, interval[, timezone])
```

**Arguments**

* `time_attr` — Date and time. [`DateTime`](/reference/data-types/datetime)
* `interval` — Window interval in Interval. [`Interval`](/reference/data-types/int-uint)
* `timezone` — Optional. Timezone name. [`String`](/reference/data-types/string)

**Returned value**

Returns the window identifier of the corresponding window. [`UInt32`](/reference/data-types/int-uint)

**Examples**

**Window ID**

```sql title=Query theme={null}
SELECT windowID(now(), toIntervalDay('1'))
```

```response title=Response theme={null}
```

<h2 id="related-content">
  Related content
</h2>

* [Time-series use-case guides](/guides/use-cases/real-time-analytics/time-series/index)