Intro to schema feature

Why we need schema

Some NoSQL databases or message queue are not strongly limited schema, so the schema cannot be obtained through the api. At this time, a schema needs to be defined to convert to SeaTunnelRowType and obtain data.

What type supported at now

Data type	Value type in Java	Description
string	java.lang.String	string
boolean	java.lang.Boolean	boolean
tinyint	java.lang.Byte	-128 to 127 regular. 0 to 255 unsigned*. Specify the maximum number of digits in parentheses.
smallint	java.lang.Short	-32768 to 32767 General. 0 to 65535 unsigned*. Specify the maximum number of digits in parentheses.
int	java.lang.Integer	All numbers from -2,147,483,648 to 2,147,483,647 are allowed.
bigint	java.lang.Long	All numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807 are allowed.
float	java.lang.Float	Float-precision numeric data from -1.79E+308 to 1.79E+308.
double	java.lang.Double	Double precision floating point. Handle most decimals.
decimal	java.math.BigDecimal	DOUBLE type stored as a string, allowing a fixed decimal point.
null	java.lang.Void	null
bytes	byte[]	bytes.
date	java.time.LocalDate	Only the date is stored. From January 1, 0001 to December 31, 9999.
time	java.time.LocalTime	Only store time. Accuracy is 100 nanoseconds.
timestamp	java.time.LocalDateTime	Stores a unique number that is updated whenever a row is created or modified. timestamp is based on the internal clock and does not correspond to real time. There can only be one timestamp variable per table.
row	org.apache.seatunnel.api.table.type.SeaTunnelRow	Row type,can be nested.
map	java.util.Map	A Map is an object that maps keys to values. The key type includes int string boolean tinyint smallint bigint float double decimal date time timestamp null , and the value type includes int string boolean tinyint smallint bigint float double decimal date time timestamp null array map.
array	ValueType[]	A array is a data type that represents a collection of elements. The element type includes int string boolean tinyint smallint bigint float double array map.

How to use schema

schema defines the format of the data,it containsfields properties. fields define the field properties,it's a K-V key-value pair, the Key is the field name and the value is field type. Here is an example.

source {
  FakeSource {
    parallelism = 2
    result_table_name = "fake"
    row.num = 16
    schema = {
      fields {
        id = bigint
        c_map = "map<string, smallint>"
        c_array = "array<tinyint>"
        c_string = string
        c_boolean = boolean
        c_tinyint = tinyint
        c_smallint = smallint
        c_int = int
        c_bigint = bigint
        c_float = float
        c_double = double
        c_decimal = "decimal(2, 1)"
        c_bytes = bytes
        c_date = date
        c_timestamp = timestamp
      }
    }
  }
}

When we should use it or not

If there is a schema configuration project in Options,the connector can then customize the schema. Like Fake Pulsar Http source connector etc.