{"id":7000,"date":"2024-03-14T04:55:28","date_gmt":"2024-03-14T04:55:28","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/"},"modified":"2025-08-02T10:50:12","modified_gmt":"2025-08-02T10:50:12","slug":"how-does-hadoop-read-csv-files","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/","title":{"rendered":"Hadoop CSV: Read with MapReduce &#038; Hive"},"content":{"rendered":"<p>While Hadoop itself doesn&#8217;t natively support reading CSV files, they can be processed using Hadoop&#8217;s MapReduce framework or tools like Hive.<\/p>\n<ol>\n<li>Reading a CSV file with the MapReduce framework:<br \/>\nOne can develop a MapReduce program to read a CSV file. Each line in the CSV file will be taken as input in the Mapper phase and split into fields. In the Reducer phase, the processed data can be written to HDFS or another storage.<\/li>\n<li>Reading CSV files using Hive:<br \/>\nHive is a data warehouse tool built on top of Hadoop, allowing users to query and manipulate data using Hive&#8217;s SQL language. One can create an external table to read the CSV file and use Hive&#8217;s query statements to work with this data.<\/li>\n<\/ol>\n<p>Example code:<\/p>\n<p>Sample code for reading a CSV file using the MapReduce framework.<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">CSVReader<\/span> {\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">CSVMapper<\/span> <span class=\"hljs-keyword\">extends<\/span> <span class=\"hljs-title class_\">Mapper<\/span>&lt;LongWritable, Text, Text, Text&gt; {\r\n        <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title function_\">map<\/span><span class=\"hljs-params\">(LongWritable key, Text value, Context context)<\/span> <span class=\"hljs-keyword\">throws<\/span> IOException, InterruptedException {\r\n            <span class=\"hljs-type\">String<\/span> <span class=\"hljs-variable\">line<\/span> <span class=\"hljs-operator\">=<\/span> value.toString();\r\n            String[] fields = line.split(<span class=\"hljs-string\">\",\"<\/span>);\r\n            <span class=\"hljs-comment\">\/\/ \u5904\u7406CSV\u6587\u4ef6\u4e2d\u7684\u6bcf\u4e00\u884c\u6570\u636e<\/span>\r\n            context.write(<span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Text<\/span>(fields[<span class=\"hljs-number\">0<\/span>]), <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Text<\/span>(fields[<span class=\"hljs-number\">1<\/span>]));\r\n        }\r\n    }\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title function_\">main<\/span><span class=\"hljs-params\">(String[] args)<\/span> <span class=\"hljs-keyword\">throws<\/span> Exception {\r\n        <span class=\"hljs-type\">Configuration<\/span> <span class=\"hljs-variable\">conf<\/span> <span class=\"hljs-operator\">=<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Configuration<\/span>();\r\n        <span class=\"hljs-type\">Job<\/span> <span class=\"hljs-variable\">job<\/span> <span class=\"hljs-operator\">=<\/span> Job.getInstance(conf, <span class=\"hljs-string\">\"CSVReader\"<\/span>);\r\n        job.setJarByClass(CSVReader.class);\r\n        job.setMapperClass(CSVMapper.class);\r\n        job.setOutputKeyClass(Text.class);\r\n        job.setOutputValueClass(Text.class);\r\n        FileInputFormat.addInputPath(job, <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Path<\/span>(<span class=\"hljs-string\">\"input.csv\"<\/span>));\r\n        FileOutputFormat.setOutputPath(job, <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Path<\/span>(<span class=\"hljs-string\">\"output\"<\/span>));\r\n        System.exit(job.waitForCompletion(<span class=\"hljs-literal\">true<\/span>) ? <span class=\"hljs-number\">0<\/span> : <span class=\"hljs-number\">1<\/span>);\r\n    }\r\n}\r\n<\/code><\/pre>\n<p>Example code for reading a CSV file using Hive:<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">CREATE<\/span> <span class=\"hljs-keyword\">EXTERNAL<\/span> <span class=\"hljs-keyword\">TABLE<\/span> my_table (\r\n    col1 STRING,\r\n    col2 STRING,\r\n    col3 <span class=\"hljs-type\">INT<\/span>\r\n)\r\n<span class=\"hljs-type\">ROW<\/span> FORMAT DELIMITED\r\nFIELDS TERMINATED <span class=\"hljs-keyword\">BY<\/span> <span class=\"hljs-string\">','<\/span>\r\nLOCATION <span class=\"hljs-string\">'\/path\/to\/csv\/file'<\/span>;\r\n\r\n<span class=\"hljs-keyword\">SELECT<\/span> <span class=\"hljs-operator\">*<\/span> <span class=\"hljs-keyword\">FROM<\/span> my_table;\r\n<\/code><\/pre>\n<p>By using the two methods mentioned above, it is possible to read CSV files on Hadoop and perform corresponding data processing operations.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>While Hadoop itself doesn&#8217;t natively support reading CSV files, they can be processed using Hadoop&#8217;s MapReduce framework or tools like Hive. Reading a CSV file with the MapReduce framework: One can develop a MapReduce program to read a CSV file. Each line in the CSV file will be taken as input in the Mapper phase [&hellip;]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[8859,8856,8860,8858,8857],"class_list":["post-7000","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-big-data-csv","tag-hadoop-csv","tag-hadoop-file-processing","tag-hive-csv","tag-mapreduce-csv"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Hadoop CSV: Read with MapReduce &amp; Hive - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"Learn how Hadoop processes CSV files using MapReduce and Hive. Complete guide for reading CSV data in Hadoop ecosystems.\" \/>\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-does-hadoop-read-csv-files\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Hadoop CSV: Read with MapReduce &amp; Hive\" \/>\n<meta property=\"og:description\" content=\"Learn how Hadoop processes CSV files using MapReduce and Hive. Complete guide for reading CSV data in Hadoop ecosystems.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - Silicon Cloud\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/SiliCloudGlobal\/\" \/>\n<meta property=\"article:published_time\" content=\"2024-03-14T04:55:28+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-08-02T10:50:12+00:00\" \/>\n<meta name=\"author\" content=\"Isabella Edwards\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:site\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Isabella Edwards\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/\"},\"author\":{\"name\":\"Isabella Edwards\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/5579144e23c225c8188167f3e3f888dd\"},\"headline\":\"Hadoop CSV: Read with MapReduce &#038; Hive\",\"datePublished\":\"2024-03-14T04:55:28+00:00\",\"dateModified\":\"2025-08-02T10:50:12+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/\"},\"wordCount\":176,\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"keywords\":[\"Big Data CSV\",\"Hadoop CSV\",\"Hadoop File Processing\",\"Hive CSV\",\"MapReduce CSV\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/\",\"name\":\"Hadoop CSV: Read with MapReduce & Hive - Blog - Silicon Cloud\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#website\"},\"datePublished\":\"2024-03-14T04:55:28+00:00\",\"dateModified\":\"2025-08-02T10:50:12+00:00\",\"description\":\"Learn how Hadoop processes CSV files using MapReduce and Hive. Complete guide for reading CSV data in Hadoop ecosystems.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.silicloud.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Hadoop CSV: Read with MapReduce &#038; Hive\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#website\",\"url\":\"https:\/\/www.silicloud.com\/blog\/\",\"name\":\"Silicon Cloud Blog\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\",\"name\":\"Silicon Cloud Blog\",\"url\":\"https:\/\/www.silicloud.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png\",\"contentUrl\":\"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png\",\"width\":1024,\"height\":1024,\"caption\":\"Silicon Cloud Blog\"},\"image\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.facebook.com\/SiliCloudGlobal\/\",\"https:\/\/twitter.com\/SiliCloudGlobal\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/5579144e23c225c8188167f3e3f888dd\",\"name\":\"Isabella Edwards\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/d4d4dec47f553ac7961d9fa4cc9bdcdcf5b7ce5106594330b6d25c5694fdbaec?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/d4d4dec47f553ac7961d9fa4cc9bdcdcf5b7ce5106594330b6d25c5694fdbaec?s=96&d=mm&r=g\",\"caption\":\"Isabella Edwards\"},\"url\":\"https:\/\/www.silicloud.com\/blog\/author\/isabellaedwards\/\"}]}<\/script>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Hadoop CSV: Read with MapReduce & Hive - Blog - Silicon Cloud","description":"Learn how Hadoop processes CSV files using MapReduce and Hive. Complete guide for reading CSV data in Hadoop ecosystems.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/","og_locale":"en_US","og_type":"article","og_title":"Hadoop CSV: Read with MapReduce & Hive","og_description":"Learn how Hadoop processes CSV files using MapReduce and Hive. Complete guide for reading CSV data in Hadoop ecosystems.","og_url":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/","og_site_name":"Blog - Silicon Cloud","article_publisher":"https:\/\/www.facebook.com\/SiliCloudGlobal\/","article_published_time":"2024-03-14T04:55:28+00:00","article_modified_time":"2025-08-02T10:50:12+00:00","author":"Isabella Edwards","twitter_card":"summary_large_image","twitter_creator":"@SiliCloudGlobal","twitter_site":"@SiliCloudGlobal","twitter_misc":{"Written by":"Isabella Edwards","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/#article","isPartOf":{"@id":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/"},"author":{"name":"Isabella Edwards","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/5579144e23c225c8188167f3e3f888dd"},"headline":"Hadoop CSV: Read with MapReduce &#038; Hive","datePublished":"2024-03-14T04:55:28+00:00","dateModified":"2025-08-02T10:50:12+00:00","mainEntityOfPage":{"@id":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/"},"wordCount":176,"publisher":{"@id":"https:\/\/www.silicloud.com\/blog\/#organization"},"keywords":["Big Data CSV","Hadoop CSV","Hadoop File Processing","Hive CSV","MapReduce CSV"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/","url":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/","name":"Hadoop CSV: Read with MapReduce & Hive - Blog - Silicon Cloud","isPartOf":{"@id":"https:\/\/www.silicloud.com\/blog\/#website"},"datePublished":"2024-03-14T04:55:28+00:00","dateModified":"2025-08-02T10:50:12+00:00","description":"Learn how Hadoop processes CSV files using MapReduce and Hive. Complete guide for reading CSV data in Hadoop ecosystems.","breadcrumb":{"@id":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.silicloud.com\/blog\/how-does-hadoop-read-csv-files\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.silicloud.com\/blog\/"},{"@type":"ListItem","position":2,"name":"Hadoop CSV: Read with MapReduce &#038; Hive"}]},{"@type":"WebSite","@id":"https:\/\/www.silicloud.com\/blog\/#website","url":"https:\/\/www.silicloud.com\/blog\/","name":"Silicon Cloud Blog","description":"","publisher":{"@id":"https:\/\/www.silicloud.com\/blog\/#organization"},"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.silicloud.com\/blog\/#organization","name":"Silicon Cloud Blog","url":"https:\/\/www.silicloud.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png","contentUrl":"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png","width":1024,"height":1024,"caption":"Silicon Cloud Blog"},"image":{"@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/SiliCloudGlobal\/","https:\/\/twitter.com\/SiliCloudGlobal"]},{"@type":"Person","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/5579144e23c225c8188167f3e3f888dd","name":"Isabella Edwards","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/d4d4dec47f553ac7961d9fa4cc9bdcdcf5b7ce5106594330b6d25c5694fdbaec?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/d4d4dec47f553ac7961d9fa4cc9bdcdcf5b7ce5106594330b6d25c5694fdbaec?s=96&d=mm&r=g","caption":"Isabella Edwards"},"url":"https:\/\/www.silicloud.com\/blog\/author\/isabellaedwards\/"}]}},"_links":{"self":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts\/7000","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/comments?post=7000"}],"version-history":[{"count":2,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts\/7000\/revisions"}],"predecessor-version":[{"id":151773,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts\/7000\/revisions\/151773"}],"wp:attachment":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/media?parent=7000"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/categories?post=7000"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/tags?post=7000"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}