Flink CDC 自定义函数处理 SQLServer XML类型数据方案
1. 背景
因业务使用SQLServer数据库，CDC同步到doris 数仓。对于SQLServer xml类型，doris没有相应的字段对应，
可以使用json来存储xml数据。需要进行一步转换。从 flink 自定义函数入手。
2. 解决方案
- SQLServer xml 字段如下
<items><item lng="zh-CN" value="银行货到付款" /><item lng="en" value="Bank transfer on delivery" />
</items>
- doris 存储转换后的json内容
{"item": [{"lng": "zh-CN","value": "银行货到付款"},{"lng": "en","value": "Bank transfer on delivery"}]
}
- flink 自定义函数代码
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import org.apache.flink.table.functions.ScalarFunction;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;/*** 将XML转换为JSON*/
public class XmlToJson extends ScalarFunction {private Logger log = LoggerFactory.getLogger(XmlToJson.class);/*** 创建XmlMapper对象用于解析XML*/private final XmlMapper xmlMapper = new XmlMapper();public String eval(String xml) {// 将XML字符串解析为JsonNode对象JsonNode jsonNode = null;try {jsonNode = xmlMapper.readTree(xml);} catch (JsonProcessingException e) {log.error("XML解析失败", e);}// 将JsonNode对象转换为JSON字符串return jsonNode.toString();}
}
- doris 表
-- GName 为json格式
CREATE TABLE `table1` (`ID` int(11) NOT NULL COMMENT '字典表统一ID',`Name` varchar(600) NULL COMMENT '统一进行字典命名',`GName` json NULL COMMENT '采用xml存储多语言',
) ENGINE=OLAP
UNIQUE KEY(`ID`)
COMMENT '测试表'
DISTRIBUTED BY HASH(`ID`) BUCKETS AUTO
PROPERTIES (
"replication_allocation" = "tag.location.default: 1",
"is_being_synced" = "false",
"storage_format" = "V2",
"enable_unique_key_merge_on_write" = "true",
"light_schema_change" = "true",
"disable_auto_compaction" = "false",
"enable_single_replica_compaction" = "false"
);
- 注册自定义函数 sql调用转换
create temporary function xml_to_json as 'com.zfb.flink.udf.XmlToJson';INSERT INTO flink_doris (`ID`,`Name`, `GName`)
SELECT
`ID`,`Name`, xml_to_json(`GName`), `TypeID`
FROM table1;- doris json使用
selectjson_extract_string(GName, '$.item[0].value') as cn_name,*
fromtable1;
