DuckLake specifies multiple different data types for field values, and also supports nested types.
The types of columns are defined in the column_type field of the ducklake_column table.
Primitive Types
| Type | Description |
|---|---|
boolean |
True or false |
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 IEEE 754 floating-point value |
float64 |
64-bit IEEE 754 floating-point value |
decimal(P, S) |
Fixed-point decimal with precision P and scale S |
time |
Time of day, microsecond precision |
timetz |
Time of day, microsecond precision, with time zone |
date |
Calendar date |
timestamp |
Timestamp, microsecond precision |
timestamptz |
Timestamp, microsecond precision, with time zone |
timestamp_s |
Timestamp, second precision |
timestamp_ms |
Timestamp, millisecond precision |
timestamp_ns |
Timestamp, nanosecond precision |
interval |
Time interval in three different granularities: months, days, and milliseconds |
varchar |
Text |
blob |
Binary data |
json |
JSON |
uuid |
Universally unique identifier |
Nested Types
DuckLake supports nested types and primitive types. Nested types are defined recursively, i.e.,
in order to define a column of type INT[] two columns are defined. The top-level column is of type list, which has a child column of type int32.
The following nested types are supported:
| Type | Description |
|---|---|
list |
Collection of values with a single child type |
struct |
A tuple of typed values |
map |
A collection of key-value pairs |
Geometry Types
DuckLake supports geometry types using the geometry type of the Parquet format. The geometry type can store different types of spatial representations called geometry primitives, of which DuckLake supports the following:
| Geometry primitive | Description |
|---|---|
point |
A single location in coordinate space. |
linestring |
A sequence of points connected by straight line segments. |
polygon |
A planar surface defined by one exterior boundary and zero or more interior boundaries (holes). |
multipoint |
A collection of point geometries. |
multilinestring |
A collection of linestring geometries. |
multipolygon |
A collection of polygon geometries. |
linestring z |
A linestring geometry with an additional Z (elevation) coordinate for each point. |
geometrycollection |
A heterogeneous collection of geometry primitives (e.g., points, lines, polygons, etc.). |