Question

我有一个Kafka主题，大约有300万条记录。我想从中选择具有特定参数的单个记录。我一直在尝试使用Lenses进行查询，但是无法形成正确的查询。以下是1条消息的记录内容。

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现在，我想过滤出具有特定source_order_id的记录，但无法找出正确的方法。我们已经尝试通过镜头以及Kafka Tool。

下面是我们在镜头中尝试过的示例查询：

{
  "header": {
    "schemaVersionNo": "1",
  },
  "payload": {
    "modifiedDate": 1552334325212,
    "createdDate": 1552334325212,
    "createdBy": "A",
    "successful": true,
    "source_order_id": "3411976933214",
  }
}

此查询有效，但是，如果我们尝试使用如下所示的源ID，则会出现错误：

SELECT * FROM `TEST`
WHERE _vtype='JSON' AND _ktype='BYTES'
AND _sample=2 AND _sampleWindow=200 AND payload.createdBy='fms'

对我而言，通过自定义使用者使用所有300万条记录，然后对其进行遍历似乎不是一种优化的方法，因此寻找针对这种用例的任何可用解决方案。

Answer 1

由于您说过可以接受其他解决方案，因此这里是使用KSQL构建的解决方案。

首先，让我们将一些示例记录放入源主题中：

$ kafkacat -P -b localhost:9092 -t TEST <<EOF
{ "header": { "schemaVersionNo": "1" }, "payload": { "modifiedDate": 1552334325212, "createdDate": 1552334325212, "createdBy": "A", "successful": true, "source_order_id": "3411976933214" } }
{ "header": { "schemaVersionNo": "1" }, "payload": { "modifiedDate": 1552334325412, "createdDate": 1552334325412, "createdBy": "B", "successful": true, "source_order_id": "3411976933215" } }
{ "header": { "schemaVersionNo": "1" }, "payload": { "modifiedDate": 1552334325612, "createdDate": 1552334325612, "createdBy": "C", "successful": true, "source_order_id": "3411976933216" } }
EOF

使用KSQL，我们可以使用PRINT检查主题：

ksql> PRINT 'TEST' FROM BEGINNING;
Format:JSON
{"ROWTIME":1552476232988,"ROWKEY":"null","header":{"schemaVersionNo":"1"},"payload":{"modifiedDate":1552334325212,"createdDate":1552334325212,"createdBy":"A","successful":true,"source_order_id":"3411976933214"}}
{"ROWTIME":1552476232988,"ROWKEY":"null","header":{"schemaVersionNo":"1"},"payload":{"modifiedDate":1552334325412,"createdDate":1552334325412,"createdBy":"B","successful":true,"source_order_id":"3411976933215"}}
{"ROWTIME":1552476232988,"ROWKEY":"null","header":{"schemaVersionNo":"1"},"payload":{"modifiedDate":1552334325612,"createdDate":1552334325612,"createdBy":"C","successful":true,"source_order_id":"3411976933216"}}

然后在该主题上声明一个模式，这使我们能够对它运行SQL：

ksql> CREATE STREAM TEST (header STRUCT<schemaVersionNo VARCHAR>, 
                          payload STRUCT<modifiedDate BIGINT, 
                                        createdDate BIGINT, 
                                        createdBy VARCHAR, 
                                        successful BOOLEAN, 
                                        source_order_id VARCHAR>) 
                          WITH (KAFKA_TOPIC='TEST', 
                                VALUE_FORMAT='JSON');

Message
----------------
Stream created
----------------

告诉KSQL使用主题中的所有数据：

ksql> SET 'auto.offset.reset' = 'earliest';
Successfully changed local property 'auto.offset.reset' to 'earliest'. Use the UNSET command to revert your change.

现在我们可以选择所有数据：

ksql> SELECT * FROM TEST;
1552475910106 | null | {SCHEMAVERSIONNO=1} | {MODIFIEDDATE=1552334325212, CREATEDDATE=1552334325212, CREATEDBY=A, SUCCESSFUL=true, SOURCE_ORDER_ID=3411976933214}
1552475910106 | null | {SCHEMAVERSIONNO=1} | {MODIFIEDDATE=1552334325412, CREATEDDATE=1552334325412, CREATEDBY=B, SUCCESSFUL=true, SOURCE_ORDER_ID=3411976933215}
1552475910106 | null | {SCHEMAVERSIONNO=1} | {MODIFIEDDATE=1552334325612, CREATEDDATE=1552334325612, CREATEDBY=C, SUCCESSFUL=true, SOURCE_ORDER_ID=3411976933216}
^CQuery terminated

或者我们可以选择使用->符号来查询它，以访问模式中的嵌套字段：

ksql> SELECT * FROM TEST 
        WHERE PAYLOAD->CREATEDBY='A';
1552475910106 | null | {SCHEMAVERSIONNO=1} | {MODIFIEDDATE=1552334325212, CREATEDDATE=1552334325212, CREATEDBY=A, SUCCESSFUL=true, SOURCE_ORDER_ID=3411976933214}

除了选择所有记录之外，您还可以只返回感兴趣的字段：

ksql> SELECT payload FROM TEST 
        WHERE PAYLOAD->source_order_id='3411976933216';
{MODIFIEDDATE=1552334325612, CREATEDDATE=1552334325612, CREATEDBY=C, SUCCESSFUL=true, SOURCE_ORDER_ID=3411976933216}

使用KSQL，您可以将任何SELECT语句的结果写入一个新主题，该语句将使用所有现有消息以及源主题中每个新消息（根据声明的SELECT进行过滤和处理）填充它声明：

ksql> CREATE STREAM TEST_CREATED_BY_A AS
        SELECT * FROM TEST WHERE PAYLOAD->CREATEDBY='A';

Message
----------------------------
Stream created and running
----------------------------

列出有关Kafka集群的主题：

ksql> SHOW TOPICS;

Kafka Topic            | Registered | Partitions | Partition Replicas | Consumers | ConsumerGroups
----------------------------------------------------------------------------------------------------
orders                 | true       | 1          | 1                  | 1         | 1
pageviews              | false      | 1          | 1                  | 0         | 0
products               | true       | 1          | 1                  | 1         | 1
TEST                   | true       | 1          | 1                  | 1         | 1
TEST_CREATED_BY_A      | true       | 4          | 1                  | 0         | 0

打印新主题的内容：

ksql> PRINT 'TEST_CREATED_BY_A' FROM BEGINNING;
Format:JSON
{"ROWTIME":1552475910106,"ROWKEY":"null","HEADER":{"SCHEMAVERSIONNO":"1"},"PAYLOAD":{"MODIFIEDDATE":1552334325212,"CREATEDDATE":1552334325212,"CREATEDBY":"A","SUCCESSFUL":true,"SOURCE_ORDER_ID":"3411976933214"}}

需要根据特定关键字过滤掉Kafka记录

1 个答案: