Data Types#

DataFusion uses Arrow, and thus the Arrow type system, for query execution. The SQL types from sqlparser-rs are mapped to Arrow data types according to the following table. This mapping occurs when defining the schema in a CREATE EXTERNAL TABLE command or when performing a SQL CAST operation.

For background on extension types and custom metadata, see the Implementing User Defined Types and Custom Metadata in DataFusion blog.

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

select arrow_typeof(interval '1 month');
+---------------------------------------------------------------------+
| arrow_typeof(IntervalMonthDayNano("79228162514264337593543950336")) |
+---------------------------------------------------------------------+
| Interval(MonthDayNano)                                              |
+---------------------------------------------------------------------+

You can cast a SQL expression to a specific Arrow type using the arrow_cast function For example, to cast the output of now() to a Timestamp with second precision:

select arrow_cast(now(), 'Timestamp(s)') as "now()";
+---------------------+
| now()               |
+---------------------+
| 2025-10-24T20:02:45 |
+---------------------+

The older syntax still works as well:

select arrow_cast(now(), 'Timestamp(Second, None)') as "now()";
+---------------------+
| now()               |
+---------------------+
| 2023-03-03T17:19:21 |
+---------------------+

Character Types#

SQL DataType	Arrow DataType
`CHAR`	`Utf8`
`VARCHAR`	`Utf8`
`TEXT`	`Utf8`
`STRING`	`Utf8`

Numeric Types#

SQL DataType	Arrow DataType
`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`
`DECIMAL(precision, scale)`	`Decimal128(precision, scale)`

Date/Time Types#

SQL DataType	Arrow DataType
`DATE`	`Date32`
`TIME`	`Time64(Nanosecond)`
`TIMESTAMP`	`Timestamp(Nanosecond, None)`
`INTERVAL`	`Interval(IntervalMonthDayNano)`

Boolean Types#

SQL DataType	Arrow DataType
`BOOLEAN`	`Boolean`

Binary Types#

SQL DataType	Arrow DataType
`BYTEA`	`Binary`

You can create binary literals using a hex string literal such as X'1234' to create a Binary value of two bytes, 0x12 and 0x34.

Unsupported SQL Types#

SQL Data Type	Arrow DataType
`UUID`	Not yet supported
`BLOB`	Not yet supported
`CLOB`	Not yet supported
`BINARY`	Not yet supported
`VARBINARY`	Not yet supported
`REGCLASS`	Not yet supported
`NVARCHAR`	Not yet supported
`CUSTOM`	Not yet supported
`ARRAY`	Not yet supported
`ENUM`	Not yet supported
`SET`	Not yet supported
`DATETIME`	Not yet supported

Supported Arrow Types#

The following types are supported by the arrow_typeof function:

Arrow Type
`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)`