Question

我遇到了一个问题，我在Flink-SQL中无法从查询中获得结果。

我在两个Kafka主题中存储了一些信息，我想将它们存储在两个表中，并以流方式在它们之间执行联接。

这些是我的flink说明：

        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        StreamTableEnvironment tableEnv = TableEnvironment.getTableEnvironment(env);
        // configure Kafka consumer
        Properties props = new Properties();
        props.setProperty("bootstrap.servers", "localhost:9092"); // Broker default host:port
        props.setProperty("group.id", "flink-consumer"); // Consumer group ID

        FlinkKafkaConsumer011<Blocks> flinkBlocksConsumer = new FlinkKafkaConsumer011<>(args[0], new BlocksSchema(), props);
        flinkBlocksConsumer.setStartFromEarliest();

        FlinkKafkaConsumer011<Transactions> flinkTransactionsConsumer = new FlinkKafkaConsumer011<>(args[1], new TransactionsSchema(), props);
        flinkTransactionsConsumer.setStartFromEarliest();

        DataStream<Blocks> blocks = env.addSource(flinkBlocksConsumer);

        DataStream<Transactions> transactions = env.addSource(flinkTransactionsConsumer);

        tableEnv.registerDataStream("blocksTable", blocks);
        tableEnv.registerDataStream("transactionsTable", transactions);

这是我的SQL查询：

Table sqlResult
   = tableEnv.sqlQuery(
       "SELECT block_timestamp,count(tx_hash) " +
       "FROM blocksTable " +
       "JOIN transactionsTable " +
       "ON blocksTable.block_hash=transactionsTable.tx_hash " +
       "GROUP BY blocksTable.block_timestamp");
DataStream<Test> resultStream = tableEnv
        .toRetractStream(sqlResult,Row.class)
        .map(t -> {
             Row r = t.f1;
             String field2 = r.getField(0).toString();
             long count = Long.valueOf(r.getField(1).toString());
             return new Test(field2,count);
             })
        .returns(Test.class);

然后，我打印结果：

resultStream.print();

但是我没有得到任何答案，我的程序被卡住了...

对于用于序列化和反序列化的模式，这是我的测试类，用于存储查询的结果（两个字段分别为string和long，分别代表block_timestamp和count）：

public class TestSchema implements DeserializationSchema<Test>, SerializationSchema<Test> {


    @Override
    public Test deserialize(byte[] message) throws IOException {
        return Test.fromString(new String(message));
    }

    @Override
    public boolean isEndOfStream(Test nextElement) {
        return false;
    }

    @Override
    public byte[] serialize(Test element) {
        return element.toString().getBytes();
    }

    @Override
    public TypeInformation<Test> getProducedType() {
        return TypeInformation.of(Test.class);
    }
}

对于BlockSchema和TransactionsSchema类，这是相同的原理。

您知道为什么我无法获得查询结果吗？我应该用BatchExecutionEnvironment测试吗？

无法从flink SQL查询获得结果

0 个答案: