amazon-kinesis - Kinesis 分区键始终位于同一个分片中

Question

我有一个带有 2 个分片的 kinesis 流，如下所示:

{
    "StreamDescription": {
        "StreamStatus": "ACTIVE",
        "StreamName": "my-stream",
        "Shards": [
            {
                "ShardId": "shardId-000000000001",
                "HashKeyRange": {
                    "EndingHashKey": "17014118346046923173168730371587",
                    "StartingHashKey": "0"
                },
            {
                "ShardId": "shardId-000000000002",
                "HashKeyRange": {
                    "EndingHashKey": "340282366920938463463374607431768211455",
                    "StartingHashKey": "17014118346046923173168730371588"
                },
        ]
    }
}

发送方设置一个分区，通常是一个 UUID。它总是落在上面的 shard-002 中，这使得系统没有负载平衡，因此不可扩展。

作为旁注，kinesis 使用 md5sum 分配一条记录，然后将其发送到包含其范围内结果散列的分片。事实上，当我在我使用的 UUId 上测试它时，它们确实总是落在同一个分片中。

echo -n 80f6302fca1e48e590b09af84f3150d3 | md5sum
4527063413b015ade5c01d88595eec11  

17014118346046923173168730371588 < 4527063413b015ade5c01d88595eec11 < 340282366920938463463374607431768211455

关于如何解决这个问题的任何想法？

Answer 1

首先看这个问答:How to decide total number of partition keys in AWS kinesis stream?

关于你的情况；您有 2 个分片，但它们的哈希键范围不相等。

分片 1 的分区键数包含:

17014118346046923173168730371587 - 0 = 17014118346046923173168730371587

分片 2 的分区键数包含:

340282366920938463463374607431768211455 - 17014118346046923173168730371587 = 34028234990682015174368201517436837

这两者有很大的不同；

17014118346046923173168730371587:17 x 10^30

340282349906820117416451434263037839868:34 x 10^37

如果分片 1 介于“0 - 170141183460469231731687303715884105727”之间，分片 2 介于“1701411834604692317316873037157864637373637373646373637363736373637373730373637373737373737373737360373737373605727”之间，那就太棒了。

您可能使用过台式机或其他精度较低的计算器。试试更好的计算器。看下面的例子；

package com.cagricelebi.kinesis.core.utils;

import java.math.BigInteger;

public class MyCalc {

    public static void main(String[] args) {
        try {

            String num1 = "340282366920938463463374607431768211455";
            String num2 = "-17014118346046923173168730371587";

            String diff = bigCalc(num1, num2, "1", "1");
            System.out.println("result1 : " + diff); // 340282349906820117416451434263037839868

            String optimumHalf = bigCalc(num1, "0", "1", "2");
            System.out.println("result2 : " + optimumHalf); // 170141183460469231731687303715884105727

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Basic calculator.
     * First adds up first two elements, than multiplies the summation.
     * The result is the division of the multilication to divisor.
     *
     * @param bigInt A
     * @param bigInt2 B
     * @param multiplicator C
     * @param divisor D
     * @return ((A+B)*C)/D
     */
    private static String bigCalc(String bigInt, String bigInt2, String multiplicator, String divisor) {
        BigInteger summation = new BigInteger(bigInt).add(new BigInteger(bigInt2));
        BigInteger multiplication = summation.multiply(new BigInteger(multiplicator));
        BigInteger division = multiplication.divide(new BigInteger(divisor));
        return division.toString();
    }

}