flinksqlbug : AggregateFunction udf Could not extract a data type from_unable to extract a type inference from method-优快云博客

本文链接：https://blog.youkuaiyun.com/Direction_Wind/article/details/136020949

这篇博客探讨了在使用 Flink SQL 时遇到的 AggregateFunction 类型推断错误，特别是关于 `CollectSetSort` 函数的问题。错误主要涉及类型不匹配和对 ArrayList 的不可访问字段。解决方案包括使用原始类型而非封装类型，并在 UDF 中返回 List 接口来避免访问私有方法的限制。

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org.apache.flink.table.api.ValidationException: SQL validation failed. An error occurred in the type inference logic of function ‘default_catalog.default_database.CollectSetSort’.
org.apache.flink.table.api.ValidationException: An error occurred in the type inference logic of function ‘default_catalog.default_database.CollectSetSort’.
org.apache.flink.table.api.ValidationException: Could not extract a valid type inference for function class ‘com.xiaomi.cloud.streaming.computing.udagg.CollectSetSort’. Please check for implementation mistakes and/or provide a corresponding hint.
org.apache.flink.table.api.ValidationException: Error in extracting a signature to accumulator mapping.
org.apache.flink.table.api.ValidationException: Unable to extract a type inference from method:
public void com.xiaomi.cloud.streaming.computing.udagg.CollectSetSort.accumulate(java.util.ArrayList,java.lang.Integer)
org.apache.flink.table.api.ValidationException: Could not extract a data type from ‘java.util.ArrayList<java.lang.Integer>’ in generic class ‘org.apache.flink.table.functions.AggregateFunction’ in class com.xiaomi.cloud.streaming.computing.udagg.CollectSetSort. Please pass the required data type manually or allow RAW types.
org.apache.flink.table.api.ValidationException: Could not extract a data type from ‘java.util.ArrayList<java.lang.Integer>’. Interpreting it as a structured type was also not successful.
org.apache.flink.table.api.ValidationException: Field ‘size’ of class ‘java.util.ArrayList’ is mutable but is neither publicly accessible nor does it have a corresponding setter method.

这个报错org.apache.flink.table.api.ValidationException: Could not extract a data type from ‘java.util.ArrayList<java.lang.Integer>’ in generic class ‘org.apache.flink.table.functions.AggregateFunction’ in class com.xiaomi.cloud.streaming.computing.udagg.CollectSetSort. Please pass the required data type manually or allow RAW types.

是因为我代码中AggregateFunction 定义的参数是 extends AggregateFunction<String, ArrayList>
java中的数据类型分两种一个是基本类一个是封装类。例如数据类型int是Java中的基本数据类型，而Integer是int的封装类。

这里我用了封装类，导致无法解析数据类型，改用了 java.lang.long 直接声明引用就可以了。

另一个报错
org.apache.flink.table.api.ValidationException: Field ‘size’ of class ‘java.util.ArrayList’ is mutable but is neither publicly accessible nor does it have a corresponding setter method.

这是因为 ArrayList是封装类型，在udf中访问其中的私有方法访问不到，所以应该用 List ，在创建的时候

在这里插入图片描述
返回List接口就可以了