Data Types¶

Lance supports a subset of Trino data types. This page documents the supported types and their mappings.

Supported Types¶

Trino Type	Lance Type	Description
`BIGINT`	Int64	64-bit signed integer
`INTEGER`	Int32	32-bit signed integer
`DOUBLE`	Float64	64-bit IEEE 754 floating point
`REAL`	Float32	32-bit IEEE 754 floating point
`VARCHAR`	Utf8	Variable-length Unicode string
`BOOLEAN`	Boolean	True or false
`DATE`	Date32	Calendar date (days since epoch)
`VARBINARY`	Binary	Variable-length binary data
`ARRAY<T>`	List	Array of elements of type T

Type Examples¶

Numeric types¶

CREATE TABLE lance.default.numbers (
    big_num BIGINT,
    int_num INTEGER,
    float_num REAL,
    double_num DOUBLE
);

INSERT INTO lance.default.numbers VALUES
    (9223372036854775807, 2147483647, 3.14, 3.141592653589793);

String types¶

CREATE TABLE lance.default.strings (
    name VARCHAR,
    description VARCHAR
);

INSERT INTO lance.default.strings VALUES
    ('Alice', 'A user named Alice'),
    ('Bob', 'Another user');

Boolean type¶

CREATE TABLE lance.default.flags (
    id BIGINT,
    is_active BOOLEAN,
    is_verified BOOLEAN
);

INSERT INTO lance.default.flags VALUES
    (1, true, false),
    (2, false, true);

Date type¶

CREATE TABLE lance.default.events (
    id BIGINT,
    event_date DATE
);

INSERT INTO lance.default.events VALUES
    (1, DATE '2024-01-15'),
    (2, DATE '2024-06-30');

Binary type¶

CREATE TABLE lance.default.blobs (
    id BIGINT,
    data VARBINARY
);

INSERT INTO lance.default.blobs VALUES
    (1, X'48454C4C4F');

Array type¶

CREATE TABLE lance.default.lists (
    id BIGINT,
    tags ARRAY(VARCHAR),
    scores ARRAY(BIGINT)
);

-- Note: Array writes have limited support

Unsupported Types¶

The following Trino types are not supported:

Type	Alternative
`TINYINT`	Use `INTEGER` or `BIGINT`
`SMALLINT`	Use `INTEGER` or `BIGINT`
`DECIMAL`	Use `DOUBLE`
`CHAR(n)`	Use `VARCHAR`
`TIME`	Store as `VARCHAR` or epoch `BIGINT`
`TIMESTAMP`	Store as `DATE` or epoch `BIGINT`
`MAP<K,V>`	Not supported
`ROW(...)`	Not supported for writes

Type Casting¶

Use CAST to convert between types:

SELECT
    CAST(id AS VARCHAR) as id_string,
    CAST(price AS BIGINT) as price_int
FROM lance.default.products;

NULL Values¶

All columns support NULL values:

INSERT INTO lance.default.users (id, name, email)
VALUES (1, 'Alice', NULL);

SELECT * FROM lance.default.users
WHERE email IS NULL;