Data Types

CnosDB SQL is implemented using Apache Arrow DataFusion, DataFusion uses Arrow types to execute queries, and the data types stored in CnosDB are mapped to SQL data types when queried.

You can see the corresponding Arrow type for any SQL expression using the arrow_typeof function. For example:

SELECT arrow_typeof('Hello CnosDB!');
+-------------------------------------+
| arrow_typeof(Utf8("Hello CnosDB!")) |
+-------------------------------------+
| Utf8                                |
+-------------------------------------+

You can also convert the content in the SQL expression to a specified Arrow type, such as converting Timestamp type to Date32:

SELECT arrow_cast(now(), 'Date32');
+------------+
| now()      |
+------------+
| 2024-03-05 |
+------------+

CnosDB can only store partial data types, for detailed information please refer to CREATE DATABASE.

Character Types

SQL Data Types	Arrow Data Type
CHAR	Utf8
VARCHAR	Utf8
TEXT	Utf8
STRING	Utf8

Numeric Types

SQL Data Types	Arrow Data Type
TINYINT	Int8
SMALLINT	Int16
INT or INTEGER	Int32
BIGINT	Int64
TINYINT UNSIGNED	UInt8
SMALLINT UNSIGNED	UInt16
INT UNSIGNED or INTEGER UNSIGNED	UInt32
BIGINT UNSIGNED	UInt64
FLOAT	Float32
REAL	Float32
DOUBLE	Float64

Date/Time Types

SQL Data Types	Arrow Data Type
DATE	Date32
TIME	Time64(Nanosecond)
TIMESTAMP	Timestamp(Nanosecond, None)
INTERVAL	Interval(MonthDayNano)

Boolean Types

SQL Data Types	Arrow Data Type
BOOLEAN	Boolean

Binary Types

SQL Data Types	Arrow Data Type
BYTEA	Binary

Unsupported SQL Types

SQL Data Types	Arrow Data Type
UUID	Unsupported
BLOB	Unsupported
CLOB	Unsupported
BINARY	Unsupported
VARBINARY	Unsupported
REGCLASS	Unsupported
NVARCHAR	Unsupported
CUSTOM	Unsupported
ARRAY	Unsupported
ENUM	Unsupported
SET	Unsupported
DATETIME	Unsupported

Supported Arrow Types

The following types are supported by the ARROW_TYPEOF function:

Arrow Types
Null
Boolean
Int8
Int16
Int32
Int64
UInt8
UInt16
UInt32
UInt64
Float16
Float32
Float64
Utf8
LargeUtf8
Binary
Timestamp(Second, None)
Timestamp(Millisecond, None)
Timestamp(Microsecond, None)
Timestamp(Nanosecond, None)
Time32
Time64
Duration(Second)
Duration(Millisecond)
Duration(Microsecond)
Duration(Nanosecond)
Interval(YearMonth)
Interval(DayTime)
Interval(MonthDayNano)
FixedSizeBinary(<len>) (e.g. FixedSizeBinary(16))
Decimal128(<precision>, <scale>) e.g. Decimal128(3, 10)
Decimal256(<precision>, <scale>) e.g. Decimal256(3, 10)