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BOOLEAN

Description​

BOOLEAN (alias: BOOL) is a data type in DataKanu Warehouse that represents boolean values: true and false.

Internally, BOOLEAN is stored as a uint8 value, where 0 represents false and 1 represents true.

Unlike MySQL where BOOLEAN is an alias for TINYINT(1), DataKanu Warehouse treats BOOLEAN as a separate data type, similar to PostgreSQL, Oracle, and other database systems.

Value Range​

BOOLEAN values can only be:

  • true (represented as 1 when displayed)
  • false (represented as 0 when displayed)

In memory, BOOLEAN type only exists as 0 or 1, with no other possible values.

Literal Values​

In DataKanu Warehouse, you can use the keywords true and false (case-insensitive) to represent boolean literal values:

mysql> select TrUe, False, true;
+------+-------+------+
| TrUe | False | true |
+------+-------+------+
|    1 |     0 |    1 |
+------+-------+------+

Supported Operations​

Logical Operations​

BOOLEAN type supports logical operations such as AND, OR, NOT, and XOR:

mysql> select true AND false, true OR false, NOT true, true XOR false;
+----------------+---------------+----------+----------------+
| true AND false | true OR false | NOT true | true XOR false |
+----------------+---------------+----------+----------------+
|              0 |             1 |        0 |              1 |
+----------------+---------------+----------+----------------+

Arithmetic Operations​

While BOOLEAN doesn't directly support arithmetic operations, expressions like true + true will work due to implicit type conversion:

mysql> select true + true;
+-------------+
| true + true |
+-------------+
|           2 |
+-------------+

This works because the boolean values are implicitly cast to SMALLINT: CAST(TRUE AS smallint) + CAST(TRUE AS smallint).

Type Conversion​

It's important to note that BOOLEAN is not equivalent to TINYINT in DataKanu Warehouse, even though they may appear similar due to MySQL conventions.

When inserting a boolean literal into a TINYINT column, implicit type conversion occurs:

CREATE TABLE test_boolean(
    u8 TINYINT
)
properties("replication_num" = "1");

mysql> insert into test_boolean values(true);

In this example, the boolean literal true is converted to a TINYINT value.

Keywords​

BOOL, BOOLEAN