# MAP type
<a name="map_type"></a>

Use the MAP type to represent values comprising a set of key-value pairs. 

```
map(keyType, valueType, valueContainsNull)
```

`keyType`: the data type of keys 

`valueType`: the data type of values

Keys aren't allowed to have `null` values. Use `valueContainsNull` to indicate if values of a MAP type value can have `null` values.