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46 lines
2.0 KiB
Markdown
46 lines
2.0 KiB
Markdown
---
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toc_priority: 141
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---
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# deltaSumTimestamp {#agg_functions-deltasumtimestamp}
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Adds the difference between consecutive rows. If the difference is negative, it is ignored.
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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.
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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.
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**Syntax**
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``` sql
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deltaSumTimestamp(value, timestamp)
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```
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**Arguments**
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- `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).
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- `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).
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**Returned value**
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- Accumulated differences between consecutive values, ordered by the `timestamp` parameter.
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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).
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**Example**
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Query:
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```sql
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SELECT deltaSumTimestamp(value, timestamp)
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FROM (SELECT number AS timestamp, [0, 4, 8, 3, 0, 0, 0, 1, 3, 5][number] AS value FROM numbers(1, 10));
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```
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Result:
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``` text
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┌─deltaSumTimestamp(value, timestamp)─┐
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│ 13 │
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└─────────────────────────────────────┘
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```
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