Nullable(T)¶

Allows to store special marker (NULL) that denotes “missing value” alongside normal values allowed by T. For example, a Nullable(Int8) type column can store Int8 type values, and the rows that do not have a value will store NULL.

T can’t be any of the composite data types Array, Map and Tuple but composite data types can contain Nullable type values, e.g. Array(Nullable(Int8)).

A Nullable type field can’t be included in table indexes.

NULL is the default value for any Nullable type.

Finding NULL¶

You can find NULL values in a column by using null subcolumn without reading the whole column. It returns 1 if the corresponding value is NULL and 0 otherwise.