Data Types

Kylin supports a wide range of data types to meet various use case requirements. In this chapter, we provide an overview of the data types supported by Kylin, covering different categories such as numeric, string, date, and more specialized data formats. These data types are essential for ensuring compatibility and efficiency in query execution and data storage.

Supported Data Types

Data Types	Description	Range of Numbers
tinyint	Small integer numbers.	(-128，127)
smallint	Small integer numbers.	(-32,768，32,767)
int/integer	Integer numbers.	(-2,147,483,648，2,147,483,647)
bigint	Large integer numbers.	(-9,223,372,036,854,775,808，9,223,372,036,854,775,807)
float	Single-precision floating point numbers.	(-3.402823466E+38，-1.175494351E-38)，0，(1.175494351E-38，3.402823466351E+38)
double	Double-precision floating point numbers.	(-1.7976931348623157E+308，-2.2250738585072014E-308)，0，(2.2250738585072014E-308，1.797693134 8623157E+308)
decimal	An exact numeric data type defined by its precision (total number of digits) and scale (number of digits to the right of the decimal point).	---
timestamp	Values comprising values of fields year, month, day, hour, minute, and second, with the session local time-zone. The timestamp value represents an absolute point in time.	---
date	Values comprising values of fields year, month and day, without a time-zone	---
varchar	Variable length string	---
char	Fixed length string	---
boolean	Boolean values	---

Note

When working with double type data, there is a potential issue with precision accuracy. This is due to the way floating-point numbers are represented in computer systems, which can lead to rounding errors or small inaccuracies in calculations, especially when dealing with very large or very small values. It's important to be mindful of this limitation when performing operations that require high precision, and consider alternative data types such as decimal for cases where exact accuracy is critical.

Example of Date

Three methods are available for querying date types. The following examples demonstrate how to query the LO_ORDERDATE field in the SSB.P_LINEORDER table.

Method 1: Date Literal

SELECT
    LO_LINENUMBER,
    LO_ORDERDATE,
    LO_ORDTOTALPRICE
FROM
    SSB.P_LINEORDER
WHERE
    LO_ORDERDATE = DATE '1992-06-03';

Method 2: Explicit Date Cast

SELECT
    LO_LINENUMBER,
    LO_ORDERDATE,
    LO_ORDTOTALPRICE
FROM
    SSB.P_LINEORDER
WHERE
    LO_ORDERDATE = CAST('1992-06-03' AS DATE);

Method 3: Implicit Date Cast

SELECT
    LO_LINENUMBER,
    LO_ORDERDATE,
    LO_ORDTOTALPRICE
FROM
    SSB.P_LINEORDER
WHERE
    LO_ORDERDATE = '1992-06-03';

NOTE

The implicit date cast method relies on Kylin to automatically convert the string to a date. While this method is convenient, it may not always produce the desired results, especially when working with dates in different formats. The explicit date cast method provides more control over the conversion process.