{"id":28059,"date":"2024-03-16T09:39:34","date_gmt":"2024-03-16T09:39:34","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-to-use-flinksql-to-read-data-from-kafka\/"},"modified":"2024-03-22T12:32:20","modified_gmt":"2024-03-22T12:32:20","slug":"how-to-use-flinksql-to-read-data-from-kafka","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-to-use-flinksql-to-read-data-from-kafka\/","title":{"rendered":"How to use FlinkSQL to read data from Kafka?"},"content":{"rendered":"

To use Flink SQL to read Kafka data, you need to follow the steps below:<\/p>\n

    \n
  1. Add the Kafka dependency to the pom.xml file in the Flink project.<\/li>\n<\/ol>\n
    <dependency<\/span>><\/span>\r\n    <groupId<\/span>><\/span>org.apache.flink<\/groupId<\/span>><\/span>\r\n    <artifactId<\/span>><\/span>flink-connector-kafka_2.12<\/artifactId<\/span>><\/span>\r\n    <version<\/span>><\/span>${flink.version}<\/version<\/span>><\/span>\r\n<\/dependency<\/span>><\/span>\r\n<\/code><\/pre>\n
    Ensure that ${flink.version} is the version number of Flink.<\/p>\n
      \n
    1. Set up an execution environment for Flink SQL.<\/li>\n<\/ol>\n
      StreamExecutionEnvironment<\/span> env<\/span> =<\/span> StreamExecutionEnvironment.getExecutionEnvironment();\r\nStreamTableEnvironment<\/span> tEnv<\/span> =<\/span> StreamTableEnvironment.create(env);\r\n<\/code><\/pre>\n
        \n
      1. Register a Kafka table in Flink SQL.<\/li>\n<\/ol>\n
        String<\/span> createTableSql<\/span> =<\/span> \"CREATE TABLE kafka_table (\\n\"<\/span> +\r\n        \"  key STRING,\\n\"<\/span> +\r\n        \"  value STRING\\n\"<\/span> +\r\n        \") WITH (\\n\"<\/span> +\r\n        \"  'connector' = 'kafka',\\n\"<\/span> +\r\n        \"  'topic' = 'your_topic',\\n\"<\/span> +\r\n        \"  'properties.bootstrap.servers' = 'your_bootstrap_servers',\\n\"<\/span> +\r\n        \"  'properties.group.id' = 'your_group_id',\\n\"<\/span> +\r\n        \"  'format' = 'json',\\n\"<\/span> +\r\n        \"  'scan.startup.mode' = 'earliest-offset'\\n\"<\/span> +\r\n        \")\"<\/span>;\r\ntEnv.executeSql(createTableSql);\r\n<\/code><\/pre>\n
        In the above code, ‘topic’ and ‘properties.bootstrap.servers’ should be replaced with your Kafka topic and the address of the bootstrap servers. ‘properties.group.id’ is the unique identifier for the Flink consumer group.<\/p>\n
        Additionally, the ‘format’ parameter specifies the data format, which can be set to the appropriate value based on the actual situation.<\/p>\n
          \n
        1. Execute a Flink SQL query.<\/li>\n<\/ol>\n
          String<\/span> querySql<\/span> =<\/span> \"SELECT * FROM kafka_table\"<\/span>;\r\nTable<\/span> result<\/span> =<\/span> tEnv.sqlQuery(querySql);\r\n<\/code><\/pre>\n
            \n
          1. Convert the query results into a DataStream.<\/li>\n<\/ol>\n
            DataStream<Row> resultStream = tEnv.toAppendStream(result, Row.class);\r\n<\/code><\/pre>\n
            Now, you can further process the resultStream, such as printing it or writing it to another system.<\/p>\n
            Finally, remember to call env.execute() to start the Flink job.<\/p>\n","protected":false},"excerpt":{"rendered":"
            To use Flink SQL to read Kafka data, you need to follow the steps below: Add the Kafka dependency to the pom.xml file in the Flink project. <dependency> <groupId>org.apache.flink<\/groupId> <artifactId>flink-connector-kafka_2.12<\/artifactId> <version>${flink.version}<\/version> <\/dependency> Ensure that ${flink.version} is the version number of Flink. Set up an execution environment for Flink SQL. StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment(); StreamTableEnvironment tEnv […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-28059","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\nHow to use FlinkSQL to read data from Kafka? - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/blog\/how-to-use-flinksql-to-read-data-from-kafka\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How to use FlinkSQL to read data from Kafka?\" \/>\n<meta property=\"og:description\" content=\"To use Flink SQL to read Kafka data, you need to follow the steps below: Add the Kafka dependency to the pom.xml file in the Flink project. <dependency> <groupId>org.apache.flink<\/groupId> <artifactId>flink-connector-kafka_2.12<\/artifactId> <version>${flink.version}<\/version> <\/dependency> Ensure that ${flink.version} is the version number of Flink. Set up an execution environment for Flink SQL. 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