mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-13 18:02:24 +00:00
46 lines
2.0 KiB
Markdown
46 lines
2.0 KiB
Markdown
---
|
|
sidebar_position: 141
|
|
---
|
|
|
|
# deltaSumTimestamp
|
|
|
|
Adds the difference between consecutive rows. If the difference is negative, it is ignored.
|
|
|
|
This function is primarily for [materialized views](../../../sql-reference/statements/create/view.md#materialized) that are ordered by some time bucket-aligned timestamp, for example, a `toStartOfMinute` bucket. Because the rows in such a materialized view will all have the same timestamp, it is impossible for them to be merged in the "right" order. This function keeps track of the `timestamp` of the values it's seen, so it's possible to order the states correctly during merging.
|
|
|
|
To calculate the delta sum across an ordered collection you can simply use the [deltaSum](../../../sql-reference/aggregate-functions/reference/deltasum.md#agg_functions-deltasum) function.
|
|
|
|
**Syntax**
|
|
|
|
``` sql
|
|
deltaSumTimestamp(value, timestamp)
|
|
```
|
|
|
|
**Arguments**
|
|
|
|
- `value` — Input values, must be some [Integer](../../data-types/int-uint.md) type or [Float](../../data-types/float.md) type or a [Date](../../data-types/date.md) or [DateTime](../../data-types/datetime.md).
|
|
- `timestamp` — The parameter for order values, must be some [Integer](../../data-types/int-uint.md) type or [Float](../../data-types/float.md) type or a [Date](../../data-types/date.md) or [DateTime](../../data-types/datetime.md).
|
|
|
|
**Returned value**
|
|
|
|
- Accumulated differences between consecutive values, ordered by the `timestamp` parameter.
|
|
|
|
Type: [Integer](../../data-types/int-uint.md) or [Float](../../data-types/float.md) or [Date](../../data-types/date.md) or [DateTime](../../data-types/datetime.md).
|
|
|
|
**Example**
|
|
|
|
Query:
|
|
|
|
```sql
|
|
SELECT deltaSumTimestamp(value, timestamp)
|
|
FROM (SELECT number AS timestamp, [0, 4, 8, 3, 0, 0, 0, 1, 3, 5][number] AS value FROM numbers(1, 10));
|
|
```
|
|
|
|
Result:
|
|
|
|
``` text
|
|
┌─deltaSumTimestamp(value, timestamp)─┐
|
|
│ 13 │
|
|
└─────────────────────────────────────┘
|
|
```
|