Map(K, V)¶

Data type Map(K, V) stores key-value pairs.

Unlike other databases, maps are not unique in Tinybird: a map can contain two elements with the same key. The reason for that is that maps are internally implemented as Array(Tuple(K, V)).

You can use use the syntax m[k] to obtain the value for key k in map m. Also, m[k] scans the map, for example the runtime of the operation is linear in the size of the map.

### Parameters

• K is the type of the Map keys. Arbitrary type except Nullable and LowCardinality nested with Nullable types.
• V is the type of the Map values. Arbitrary type.

Convert tuple to map¶

Values of type Tuple() can be cast to values of type Map() using function CAST:

Example

Query:

SELECT CAST(([1, 2, 3], ['Ready', 'Steady', 'Go']), 'Map(UInt8, String)') AS map;

Result:

┌─map───────────────────────────┐
│ {1:'Ready',2:'Steady',3:'Go'} │
└───────────────────────────────┘

Reading subcolumns of map¶

To avoid reading the entire map, you can use subcolumns keys and values in some cases.