如何将链接表保存到csv文件？

Question

我用的是Flink 1.4.0

我正在尝试将Table API查询的结果保存到CSV文件，但我收到错误。以下是详细信息：

我的输入文件如下所示:

id,species,color,weight,name 
311,canine,golden,75,dog1 
312,canine,brown,22,dog2 
313,feline,gray,8,cat1

我对此运行查询以仅选择犬类，我想将其保存到csv文件中：

ExecutionEnvironment env = 
ExecutionEnvironment.getExecutionEnvironment(); 
BatchTableEnvironment tableEnv = 
TableEnvironment.getTableEnvironment(env); 

String inputPath = "location-of-source-file"; 
CsvTableSource petsTableSource = CsvTableSource.builder() 
  .path(inputPath) 
  .ignoreFirstLine() 
  .fieldDelimiter(",") 
  .field("id", Types.INT()) 
  .field("species", Types.STRING()) 
  .field("color", Types.STRING()) 
  .field("weight", Types.DOUBLE()) 
  .field("name", Types.STRING()) 
  .build(); 

// Register our table source 
tableEnv.registerTableSource("pets", petsTableSource); 
Table pets = tableEnv.scan("pets"); 

Table counts = pets 
  .groupBy("species") 
  .select("species, species.count as count") 
  .filter("species === 'canine'"); 

// Convert to Dataset and display results
DataSet<Row> result = tableEnv.toDataSet(counts, Row.class); 
result.print(); 

// Write Results to File 
TableSink<Row> sink = new CsvTableSink("/home/hadoop/output/pets.csv", ","); 
counts.writeToSink(sink); 

当我运行此命令时，我看到数据集的结果被输出：
犬科动物，2

然而，我在输出文件中没有得到任何结果，我在下面看到了这些错误。我能做些什么来解决这个问题？谢谢

2018-05-27 13:29:17,040 INFO  [main] typeutils.TypeExtractor (TypeExtractor.java:1873) - class org.apache.flink.types.Row does not contain a getter for field fields
2018-05-27 13:29:17,040 INFO  [main] typeutils.TypeExtractor (TypeExtractor.java:1876) - class org.apache.flink.types.Row does not contain a setter for field fields
2018-05-27 13:29:17,040 INFO  [main] typeutils.TypeExtractor (TypeExtractor.java:1911) - class org.apache.flink.types.Row is not a valid POJO type because not all fields are valid POJO fields.
2018-05-27 13:29:17,047 INFO  [main] typeutils.TypeExtractor (TypeExtractor.java:1873) - class org.apache.flink.types.Row does not contain a getter for field fields
2018-05-27 13:29:17,047 INFO  [main] typeutils.TypeExtractor (TypeExtractor.java:1876) - class org.apache.flink.types.Row does not contain a setter for field fields
2018-05-27 13:29:17,047 INFO  [main] typeutils.TypeExtractor (TypeExtractor.java:1911) - class org.apache.flink.types.Row is not a valid POJO type because not all fields are valid POJO fields.

Answer 1

你可能错过了一次机会

env.execute(); 

之后

counts.writeToSink(sink);

与立即触发执行的＜code＞print（）＜/code＞相反，＜code＞writeToSink（）＜/code＞只是附加了一个sink操作符，并需要显式触发执行。

< code>TypeExtractor的< code>INFO消息“只是”告诉您,< code>Row不能用作POJO类型，但是在这里没有问题。