Flink learning 6: programming model

1. Interface layering

Flink Different levels of interfaces are provided , At the bottom is state data flow processing , The highest level is SQL

1.1 State data flow processing

Through the process function , Inherited to DataStream API in

  Stateful data stream processing interface ,

1.2 DataStream and DataSet API

The core API

DataStream Used to deal with bounded and Unbounded data flow .

DataSet API  Used to deal with bounded Data flow .

This interface provides a large number of common components

 

in addition ,

DataStream Integrate lower level functions

DataSet API Provides additional support for bounded data

 

1.3 Table API

1. Take the watch as the center , A two-dimensional table similar to a relational database
 

2. Provide comparable operations ,select, group by etc.

 3.Table API You can customize functions to extend , But in terms of expression ability , Not as good as the core API.（ however Table API The code is simpler ）

4.Table API Is to specify what the program should do , Instead of specifying the exact execution steps of the program

5.Table API It will be optimized before implementation , in addition Table API and DataStream , DataSet Seamless switching between . So in the program, you can mix only .

1.4 SQL 

Flink The most advanced encapsulation interface is flink SQL

Grammar and expressive ability are similar to Table API similar , The only difference is through the use of SQL Query language implementation program .

SQL Query and Table API Close interaction ,SQL Can be directly in Table API Query on the table created in