Data Types in ksqlDB for Confluent Platform¶

Boolean types¶

Name	Description	Backing Java type
`boolean`	value representing `true` or `false`	java.lang.Boolean

Character types¶

Name	Description	Backing Java type
`varchar`, `string`	variable-length string	java.lang.String
`bytes`	variable-length byte array	byte []

The varchar type represents a string in UTF-16 format.

Comparisons between varchar instances don’t account for locale.

The bytes type represents an array of raw bytes.

Numeric types¶

Name	Storage size	Range (min to max value)	Notes	Backing Java type
int	4 bytes	-2:sup:31 to 2:sup:31-1	typical choice for integer	Integer
bigint	8 bytes	-2:sup:63 to 2:sup:63-1	large-range integer	Long
double	8 bytes	2:sup:-1074† to (2-2:sup:-52)·2:sup:1023	variable-precision, inexact	Double
decimal	value dependent	n/a	user-specified precision, exact	BigDecimal

^† Smallest positive nonzero value

Integer types¶

The int and bigint types store integers, which are numbers without decimals. Storing values outside of the supported range results in an error.

If your values are in its range, the int type is a good choice, because its implementation has minimal overhead. If your values may be of a larger size, use bigint.

Floating-point types¶

The double data type is an inexact, variable-precision numeric type. The term “inexact” means an approximate value is stored. Storing values outside of its bounds of capacity will result in an error.

Valid ranges¶

Numeric data types have the same valid minimum and maximum values as their corresponding Java types.

Arbitrary precision types¶

The decimal type can be used to store fractional numbers with exact precision. This is useful for modeling money or other values that don’t tolerate approximate storage representations.

decimal types take two parameters: precision and scale. Precision is the maximum total number of decimal digits to be stored, including values to the left and right of the decimal point. The precision must be greater than 1. There is no default precision.

Scale is the number of decimal digits to the right of the decimal point. This number must be greater than 0 and less than or equal to the value for precision.

To declare a column of the decimal type, use the syntax:

DECIMAL(precision, scale)

Mathematical operations between double and decimal cause the decimal to be converted to a double value automatically. Converting from the decimal data type to any floating point type (double) may cause loss of precision.

Upcasting an int to a decimal produces a decimal with a precision of 10 and a scale of 0.
Upcasting a bigint to a decimal produces a decimal with a precision of 19 and a scale of 0.

Time types¶

Name	Description	Backing Java type
time	Time of day in millisecond precision	java.sql.Time
date	Calendar date independent of time zone	java.sql.Date
timestamp	Point in time in millisecond precision without timezone information	java.sql.Timestamp

Compound types¶

Note

The DELIMITED serialization format doesn’t support compound types.

Name	Description	Backing Java type
array	Sequence of values of a single type	Java native array
map	A mapping of keys to values	java.util.map
struct	A strongly-typed structured data type	org.apache.kafka.connect.data.Struct

Array¶

ARRAY<ElementType>

ksqlDB supports fields that are arrays of another type. All of the elements in the array must be of the same type. The element type can be any valid SQL type.

The elements of an array are one-indexed and can be accessed by using the [] operator passing in the index. For example, SOME_ARRAY[1] retrieves the first element from the array. For more information, see Operators.

You can define arrays within a CREATE TABLE or CREATE STREAM statement by using the syntax ARRAY<ElementType>. For example, ARRAY<INT> defines an array of integers.

Also, you can output an array from a query by using a SELECT statement. The following example creates an array from a stream named s1.

SELECT ARRAY[1, 2] FROM s1 EMIT CHANGES;

Starting in version 0.7.1, the built-in AS_ARRAY function syntax for creating arrays doesn’t work. Replace AS_ARRAY with the ARRAY constructor syntax. For example, replace this legacy query:

CREATE STREAM OUTPUT AS SELECT cube_explode(as_array(col1, col2)) VAL1, ABS(col3) VAL2 FROM TEST;

With this query:

CREATE STREAM OUTPUT AS SELECT cube_explode(array[col1, col2]) VAL1, ABS(col3) VAL2 FROM TEST;

Struct¶

STRUCT<FieldName FieldType, ...>

ksqlDB supports fields that are structs. A struct represents strongly typed structured data. A struct is an ordered collection of named fields that have a specific type. The field types can be any valid SQL type.

Access the fields of a struct by using the -> operator. For example, SOME_STRUCT->ID retrieves the value of the struct’s ID field; and SOME_STRUCT->* retrieves the values of all fields of SOME_STRUCT. For more information, see Operators.

You can define structs within a CREATE TABLE or CREATE STREAM statement by using the syntax STRUCT<FieldName FieldType, ...>. For example, STRUCT<ID BIGINT, NAME STRING, AGE INT> defines a struct with three fields, with the supplied name and type.

Also, you can output a struct from a query by using a SELECT statement. The following example creates a struct from a stream named s1.

SELECT STRUCT(f1 := v1, f2 := v2) FROM s1 EMIT CHANGES;

Map¶

MAP<KeyType, ValueType>

ksqlDB supports fields that are maps. A map has a key and value type. All of the keys must be of the same type, and all of the values must also be of the same type. Currently only STRING keys are supported. The value type can be any valid SQL type.

Access the values of a map by using the [] operator and passing in the key. For example, SOME_MAP['cost'] retrieves the value for the entry with key cost, or null For more information, see Operators.

You can define maps within a CREATE TABLE or CREATE STREAM statement by using the syntax MAP<KeyType, ValueType>. For example, MAP<STRING, INT> defines a map with string keys and integer values.

Also, you can output a map from a query by using a SELECT statement. The following example creates a map from a stream named s1.

SELECT MAP(k1:=v1, k2:=v1*2) FROM s1 EMIT CHANGES;

Custom types¶

ksqlDB supports custom types using the CREATE TYPE statements. See the CREATE TYPE docs for more information.