Data types

Polars is entirely based on Arrow data types and backed by Arrow memory arrays. This makes data processing cache-efficient and well-supported for Inter Process Communication. Most data types follow the exact implementation from Arrow, with the exception of Utf8 (this is actually LargeUtf8), Categorical, and Object (support is limited). The data types are:

Group	Type	Details
Numeric	Int8	8-bit signed integer.
	Int16	16-bit signed integer.
	Int32	32-bit signed integer.
	Int64	64-bit signed integer.
	UInt8	8-bit unsigned integer.
	UInt16	16-bit unsigned integer.
	UInt32	32-bit unsigned integer.
	UInt64	64-bit unsigned integer.
	Float32	32-bit floating point.
	Float64	64-bit floating point.
Nested	Struct	A struct array is represented as a Vec<Series> and is useful to pack multiple/heterogenous values in a single column.
	List	A list array contains a child array containing the list values and an offset array. (this is actually Arrow LargeList internally).
Temporal	Date	Date representation, internally represented as days since UNIX epoch encoded by a 32-bit signed integer.
	Datetime	Datetime representation, internally represented as microseconds since UNIX epoch encoded by a 64-bit signed integer.
	Duration	A timedelta type, internally represented as microseconds. Created when subtracting Date/Datetime.
	Time	Time representation, internally represented as nanoseconds since midnight.
Other	Boolean	Boolean type effectively bit packed.
	Utf8	String data (this is actually Arrow LargeUtf8 internally).
	Binary	Store data as bytes.
	Object	A limited supported data type that can be any value.
	Categorical	A categorical encoding of a set of strings.

To learn more about the internal representation of these data types, check the Arrow columnar format.