Flink：左键使用静态列表加入流

Question

我想将一系列尝试加入到一个静态的阻止电子邮件列表中，并按IP对结果进行分组，以便稍后统计一组相关的统计数据。结果应在每10秒后以30分钟的滑动窗口交付。以下是我尝试实现这一目标的几种方法之一：

override fun performQuery(): Table {
    val query = "SELECT ip, " +
        "COUNT(CASE WHEN success IS false THEN 1 END) AS fails, " +
        "COUNT(CASE WHEN success IS true THEN 1 END) AS successes, " +
        "COUNT(DISTINCT id) accounts, " +
        "COUNT(CASE WHEN id = 0 THEN 1 END) AS non_existing_accounts, " +
        "COUNT(CASE WHEN blockedEmail IS NOT NULL THEN 1 END) AS blocked_accounts " +
        "FROM Attempts " +
        "LEFT JOIN LATERAL TABLE(blockedEmailsList()) AS T(blockedEmail) ON TRUE " +
        "WHERE Attempts.email <> '' AND Attempts.createdAt < CURRENT_TIMESTAMP " +
        "GROUP BY HOP(Attempts.createdAt, INTERVAL '10' SECOND, INTERVAL '30' MINUTE), ip"

    return runQuery(query)
        .select("ip, accounts, fails, successes, non_existing_accounts, blocked_accounts")
}

这使用下面的用户定义的表函数，该函数已在my tableEnv中注册为BlockedEmailList：

public class BlockedEmailsList extends TableFunction<Row> {
    private Collection<String> emails;

    public BlockedEmailsList(Collection<String> emails) {
        this.emails = emails;
    }

    public Row read(String email) {
        return Row.of(email);
    }

    public void eval() {
        this.emails.forEach(email -> collect(read(email)));
    }
}

但是，它返回以下错误：

Caused by: org.apache.flink.table.api.TableException: Rowtime attributes must not be in the input rows of a regular join. As a workaround you can cast the time attributes of input tables to TIMESTAMP before.

如果我按照建议执行并将创建的时间戳转换为时间戳，我会得到以下结果：

org.apache.flink.client.program.ProgramInvocationException: The main method caused an error: Window can only be defined over a time attribute column.

我在这里发现了与这些异常相关的堆栈溢出问题，但它们涉及流和时态表，没有一个解决将流连接到静态列表的问题。

有什么想法吗？

编辑：我的用例的Flink项目中似乎有一个未解决的问题：https://cwiki.apache.org/confluence/display/FLINK/FLIP-17DataStream API的侧面输入

所以，我也接受变通建议。

Answer 1

我设法实现了一个解决我的问题的解决方法！

我没有将流式尝试与静态电子邮件列表连接起来，而是预先将每次尝试映射到一个新的尝试，并添加了一个blockedEmail属性。如果静态列表包含当前尝试的电子邮件，我将其属性设置为true。

DataStream<Attempt> attemptsStream = sourceApi.<Attempt>startStream().map(new MapFunction<Attempt, Attempt>() {
    @Override
    public Attempt map(Attempt attempt) throws Exception {
        if (blockedEmails.contains(attempt.getEmail())) {
            attempt.setBlockedEmail(true);
        }
        return attempt;
    }
});

静态列表block edEmails的类型为HashSet，因此查找将是O（1）。

最后，分组查询被调整为：

override fun performQuery(): Table {
    val query = "SELECT ip, " +
        "COUNT(CASE WHEN success IS false THEN 1 END) AS fails, " +
        "COUNT(CASE WHEN success IS true THEN 1 END) AS successes, " +
        "COUNT(DISTINCT id) accounts, " +
        "COUNT(CASE WHEN id = 0 THEN 1 END) AS non_existing_accounts, " +
        "COUNT(CASE WHEN blockedEmail IS true THEN 1 END) AS blocked_accounts " +
        "FROM Attempts " +
        "WHERE Attempts.email <> '' " +
        "GROUP BY HOP(Attempts.createdAt, INTERVAL '10' SECOND, INTERVAL '30' MINUTE), ip"

    return runQuery(query)
        .select("ip, accounts, fails, successes, non_existing_accounts, blocked_accounts")
}

到目前为止，流和静态列表之间的连接问题似乎尚未解决，但在我的案例中，上述解决方案很好地解决了这个问题。

Answer 2

Caused by: org.apache.flink.table.api.TableException: Rowtime attributes must not be in the input rows of a regular join. As a workaround you can cast the time attributes of input tables to TIMESTAMP before.

原因是横向表函数是Flink正则联接，正则联接将发送空值，例如

left:（K0, A）, right（K1, T1）  => send    (K0, A, NULL, NULL)
left:         , right（K0, T2） => retract (K0, A, NULL, NULL )  
                                   send   (K0, A, K0, T2)

因此，输入流的时间属性在连接后会丢失。

在您的情况下，您不需要TableFunction，您可以使用标量函数，例如：

 public static class BlockedEmailFunction extends ScalarFunction {
     private static List<String> blockedEmails = ...;
     public Boolean eval(String email) {
        return blockedEmails.contains(attempt.getEmail());
     }
 }


// register function
env.createTemporarySystemFunction("blockedEmailFunction", BlockedEmailFunction.class);

// call registered function in SQL and do window operation as your expected
env.sqlQuery("SELECT blockedEmailFunction(email) as status, ip, createdAt FROM Attempts");