ClickHouse/docs/en/sql-reference/aggregate-functions/reference/maxmap.md

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sidebar_position: 143
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# maxMap {#agg_functions-maxmap}

Syntax: `maxMap(key, value)` or `maxMap(Tuple(key, value))`

Calculates the maximum from `value` array according to the keys specified in the `key` array.

Passing a tuple of keys and value arrays is identical to passing two arrays of keys and values.

The number of elements in `key` and `value` must be the same for each row that is totaled.

Returns a tuple of two arrays: keys and values calculated for the corresponding keys.

Example:

``` sql
SELECT maxMap(a, b)
FROM values('a Array(Int32), b Array(Int64)', ([1, 2], [2, 2]), ([2, 3], [1, 1]))
```

``` text
┌─maxMap(a, b)──────┐
│ ([1,2,3],[2,2,1]) │
└───────────────────┘
```