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3.1 KiB
Markdown
83 lines
3.1 KiB
Markdown
---
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slug: /en/sql-reference/aggregate-functions/reference/summap
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sidebar_position: 198
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---
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# sumMap
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Totals a `value` array according to the keys specified in the `key` array. Returns a tuple of two arrays: keys in sorted order, and values summed for the corresponding keys without overflow.
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**Syntax**
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- `sumMap(key <Array>, value <Array>)` [Array type](../../data-types/array.md).
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- `sumMap(Tuple(key <Array>, value <Array>))` [Tuple type](../../data-types/tuple.md).
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Alias: `sumMappedArrays`.
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**Arguments**
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- `key`: [Array](../../data-types/array.md) of keys.
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- `value`: [Array](../../data-types/array.md) of values.
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Passing a tuple of key and value arrays is a synonym to passing separately an array of keys and an array of values.
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:::note
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The number of elements in `key` and `value` must be the same for each row that is totaled.
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:::
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**Returned Value**
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- Returns a tuple of two arrays: keys in sorted order, and values summed for the corresponding keys.
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**Example**
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First we create a table called `sum_map`, and insert some data into it. Arrays of keys and values are stored separately as a column called `statusMap` of [Nested](../../data-types/nested-data-structures/index.md) type, and together as a column called `statusMapTuple` of [tuple](../../data-types/tuple.md) type to illustrate the use of the two different syntaxes of this function described above.
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Query:
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``` sql
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CREATE TABLE sum_map(
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date Date,
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timeslot DateTime,
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statusMap Nested(
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status UInt16,
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requests UInt64
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),
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statusMapTuple Tuple(Array(Int32), Array(Int32))
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) ENGINE = Log;
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```
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```sql
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INSERT INTO sum_map VALUES
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('2000-01-01', '2000-01-01 00:00:00', [1, 2, 3], [10, 10, 10], ([1, 2, 3], [10, 10, 10])),
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('2000-01-01', '2000-01-01 00:00:00', [3, 4, 5], [10, 10, 10], ([3, 4, 5], [10, 10, 10])),
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('2000-01-01', '2000-01-01 00:01:00', [4, 5, 6], [10, 10, 10], ([4, 5, 6], [10, 10, 10])),
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('2000-01-01', '2000-01-01 00:01:00', [6, 7, 8], [10, 10, 10], ([6, 7, 8], [10, 10, 10]));
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```
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Next, we query the table using the `sumMap` function, making use of both array and tuple type syntaxes:
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Query:
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``` sql
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SELECT
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timeslot,
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sumMap(statusMap.status, statusMap.requests),
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sumMap(statusMapTuple)
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FROM sum_map
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GROUP BY timeslot
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```
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Result:
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``` text
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┌────────────timeslot─┬─sumMap(statusMap.status, statusMap.requests)─┬─sumMap(statusMapTuple)─────────┐
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│ 2000-01-01 00:00:00 │ ([1,2,3,4,5],[10,10,20,10,10]) │ ([1,2,3,4,5],[10,10,20,10,10]) │
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│ 2000-01-01 00:01:00 │ ([4,5,6,7,8],[10,10,20,10,10]) │ ([4,5,6,7,8],[10,10,20,10,10]) │
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└─────────────────────┴──────────────────────────────────────────────┴────────────────────────────────┘
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```
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**See Also**
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- [Map combinator for Map datatype](../combinators.md#-map)
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- [sumMapWithOverflow](../reference/summapwithoverflow.md)
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