ClickHouse/docs/en/sql-reference/functions/time-window-functions.md

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/en/sql-reference/functions/time-window-functions	175	Time Window

Time Window Functions

Time window functions return the inclusive lower and exclusive upper bound of the corresponding window. The functions for working with WindowView are listed below:

tumble

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

Syntax

tumble(time_attr, interval [, timezone])

Arguments

• time_attr — Date and time. DateTime.
• interval — Window interval in Interval.
• timezone — Timezone name (optional).

Returned values

• The inclusive lower and exclusive upper bound of the corresponding tumbling window. Tuple(DateTime, DateTime).

Example

Query:

SELECT tumble(now(), toIntervalDay('1'));

Result:

┌─tumble(now(), toIntervalDay('1'))─────────────┐
│ ('2024-07-04 00:00:00','2024-07-05 00:00:00') │
└───────────────────────────────────────────────┘

tumbleStart

Returns the inclusive lower bound of the corresponding tumbling window.

Syntax

tumbleStart(time_attr, interval [, timezone]);

Arguments

• time_attr — Date and time. DateTime.
• interval — Window interval in Interval.
• timezone — Timezone name (optional).

The parameters above can also be passed to the function as a tuple.

Returned values

• The inclusive lower bound of the corresponding tumbling window. DateTime, Tuple or UInt32.

Example

Query:

SELECT tumbleStart(now(), toIntervalDay('1'));

Result:

┌─tumbleStart(now(), toIntervalDay('1'))─┐
│                    2024-07-04 00:00:00 │
└────────────────────────────────────────┘

tumbleEnd

Returns the exclusive upper bound of the corresponding tumbling window.

Syntax

tumbleEnd(time_attr, interval [, timezone]);

Arguments

• time_attr — Date and time. DateTime.
• interval — Window interval in Interval.
• timezone — Timezone name (optional).

The parameters above can also be passed to the function as a tuple.

Returned values

• The inclusive lower bound of the corresponding tumbling window. DateTime, Tuple or UInt32.

Example

Query:

SELECT tumbleEnd(now(), toIntervalDay('1'));

Result:

┌─tumbleEnd(now(), toIntervalDay('1'))─┐
│                  2024-07-05 00:00:00 │
└──────────────────────────────────────┘

hop

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.

hop(time_attr, hop_interval, window_interval [, timezone])

Arguments

• time_attr — Date and time. DateTime.
• hop_interval — Positive Hop interval. Interval.
• window_interval — Positive Window interval. Interval.
• timezone — Timezone name (optional).

Returned values

• The inclusive lower and exclusive upper bound of the corresponding hopping window. Tuple(DateTime, DateTime)`.

:::note 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. :::

Example

Query:

SELECT hop(now(), INTERVAL '1' DAY, INTERVAL '2' DAY);

Result:

┌─hop(now(), toIntervalDay('1'), toIntervalDay('2'))─┐
│ ('2024-07-03 00:00:00','2024-07-05 00:00:00')      │
└────────────────────────────────────────────────────┘

hopStart

Returns the inclusive lower bound of the corresponding hopping window.

Syntax

hopStart(time_attr, hop_interval, window_interval [, timezone]);

Arguments

• time_attr — Date and time. DateTime.
• hop_interval — Positive Hop interval. Interval.
• window_interval — Positive Window interval. Interval.
• timezone — Timezone name (optional).

The parameters above can also be passed to the function as a tuple.

Returned values

• The inclusive lower bound of the corresponding hopping window. DateTime, Tuple or UInt32.

:::note 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. :::

Example

Query:

SELECT hopStart(now(), INTERVAL '1' DAY, INTERVAL '2' DAY);

Result:

┌─hopStart(now(), toIntervalDay('1'), toIntervalDay('2'))─┐
│                                     2024-07-03 00:00:00 │
└─────────────────────────────────────────────────────────┘

hopEnd

Returns the exclusive upper bound of the corresponding hopping window.

Syntax

hopEnd(time_attr, hop_interval, window_interval [, timezone]);

Arguments

• time_attr — Date and time. DateTime.
• hop_interval — Positive Hop interval. Interval.
• window_interval — Positive Window interval. Interval.
• timezone — Timezone name (optional).

The parameters above can also be passed to the function as a tuple.

Returned values

• The exclusive upper bound of the corresponding hopping window. DateTime, Tuple or UInt32.

:::note 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. :::

Example

Query:

SELECT hopEnd(now(), INTERVAL '1' DAY, INTERVAL '2' DAY);

Result:

┌─hopEnd(now(), toIntervalDay('1'), toIntervalDay('2'))─┐
│                                   2024-07-05 00:00:00 │
└───────────────────────────────────────────────────────┘

Related content

• Blog: Working with time series data in ClickHouse