debezium详解decimal.handling.mode

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decimal.handling.mode配置的作用，是配置数据库中浮点类型映射类型，
数据库浮点类型包含以下：
mysql：double\float\decimal
oracle: number

以下是来自debezium官网的原文介绍：
https://debezium.io/documentation/reference/2.5/connectors/mysql.html#mysql-connector-properties
这个配置项在debezium的版本迭代中几乎没有变化

decimal.handling.mode

precise（默认值）

Specifies how the connector should handle values for DECIMAL and NUMERIC columns:

precise (the default) represents them precisely using java.math.BigDecimal values represented in change events in a binary form.

double represents them using double values, which may result in a loss of precision but is easier to use.

string encodes values as formatted strings, which is easy to consume but semantic information about the real type is lost.

下面提供一些示例数据，及数据使用方法
以mysql为示例

CREATE TABLE `doubleV` (
  `d18_0` decimal(18,0) DEFAULT NULL,
  `d18_5` decimal(18,5) DEFAULT NULL,
  `d18_10` decimal(18,10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

INSERT INTO testdb.doubleV (d18_0,d18_5,d18_10)
	VALUES (345678901234567890,456789012345.67890,456789.0123456789);

采集作业配置

        {
            "name":"mysql_04",
            "config":{
                "connector.class":"io.debezium.connector.mysql.MySqlConnector",
                "tasks.max":"1",
                "database.hostname":"192.168.1.226",
                "database.port":"3306",
                "database.user":"root",
                "database.password":"123456",
                "database.server.name":"mysqlcdc",
                "table.include.list":"testdb.doubleV",
                "topic.prefix": "mysqlcdc",
                "database.server.id": "1",
                "decimal.handling.mode":"string",
                "schema.history.internal.kafka.bootstrap.servers":"192.168.1.103:9092",
                "schema.history.internal.kafka.topic":"mysqlcdc.history",
                "snapshot.mode":"schema_only",
                "include.schema.changes": "true"

            }
        }

    
    public static void main(String[] args) {
    	printDePrecise("BMwZIRJvCtI=", 0);
    	printDePrecise("AKJIt/nRCtI=", 5);
    	printDePrecise("EDp4zC6BFQ==", 10);
	}
    
    static void printDePrecise (String encoded, int scale) {
    	final BigDecimal decoded = new BigDecimal(new BigInteger(Base64.getDecoder().decode(encoded)), scale);
    	System.out.println(String.format("encoded: %s, scale: %s, decoded: %s", encoded, scale, decoded));
    }