[FLINK-15326] Add document description for DECIMAL(38, 18) when the sink table uses json schema

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Component/s: Table SQL / Planner
• Assignee: Unassigned
• Reporter: hehuiyuan
• Created: 19/Dec/19 10:25
• Updated: 13/Apr/21 20:30
• Resolved: 26/Dec/19 04:33

Description

Env : 

        Flink 1.9.1 

        table-planner-blink

 

Question:

If i have a kafka sink table with json schema:

 

String jsonSchema = 
"{
    type:'object',
    properties:{
        name: { type: 'string' },
        age: { type: 'integer' },
        sex: { type: 'string' }
    }
}";
JsonRowDeserializationSchema deserializationSchema = new JsonRowDeserializationSchema(jsonSchema.toString());
TypeInformation fieldTypes = deserializationSchema.getProducedType();
Kafka kafka = new Kafka.......
Schema schema = new Schema......
tableEnvironment.connect(kafka)
 .withFormat( new Json().jsonSchema(jsonSchema))
 .withSchema( schema )
 .inAppendMode()
 .registerTableSink("sink_example2")
;
String sinksql = "insert into sink_example2 select * from table2"
tableEnvironment.sqlUpdate(sinksql);

 

 

Error:

Query result schema: [name: String, age: BigDecimal, sex: String]
TableSink schema:    [name: String, age: BigDecimal, sex: String]

The table `table2` : table schema 

 

[2019-12-19 18:10:16,937] INFO t2: root
 |-- name: STRING
 |-- age: DECIMAL(10, 0)
 |-- sex: STRING
 

 

When i use kafka to read data for json schema , i understand the integer type in json is mapped  DECIMAL(38, 18) in flink table

 

|-- name: STRING
 |-- age: DECIMAL(38, 18)
 |-- sex: STRING

 

That's why i  know to set decimal precision

String sinksql = "insert into sink_example2 select name CAST(age as decimal(38,18) ) as age, sex from table2"

JSON format needs to pay attention to this problem.

 

Issue Links

• is duplicated by: FLINK-15313 Can not insert decimal with precision into sink using TypeInformation
• relates to: FLINK-15313 Can not insert decimal with precision into sink using TypeInformation