mapreduce map-阿里云

MapReduce中的Map和Reduce函数分别是什么作用？

MapReduce中的Map和Reduce函数分别是什么作用？在MapReduce中，Map函数和Reduce函数是两个核心操作，用于处理大规模数据集。Map函数的作用是将输入数据集划分为若干个小数据块，并将每个数据块映射为(key, value)对。Map函数接受一个输入数据块，对其进行处理，并生...

32 MAPREDUCE的map端join算法实现

原理阐述适用于关联表中有小表的情形；可以将小表分发到所有的map节点，这样，map节点就可以在本地对自己所读到的大表数据进行join并输出最终结果，可以大大提高join操作的并发度，加快处理速度。实现示例1.在mapper类中预先定义好小表，进行join2.引入实际场景中的解决方案：一次加载数据库或...

Hadoop 分布式计算框架 MapReduce

89 课时 |

745 人已学 |

加入学习

Hadoop框架下MapReduce中的map个数如何控制

一个job的map阶段并行度由客户端在提交job时决定客户端对map阶段并行度的规划基本逻辑为：一、将待处理的文件进行逻辑切片（根据处理数据文件的大小，划分多个split），然后每一个split分配一个maptask并行处理实例二、具体切片规划是由FileInputFormat实现类的getSpli...

MapReduce执行机制之Map和Reduce源码分析

1、Mapper 类 * Maps input key/value pairs to a set of intermediate key/value pairs. * * <p>Maps are the individual tasks which transform input rec...

map函数中为什么忽略键？map函数输出什么时候由MapReduce框架处理呀？

MapReduce中抽取年份和气温map和reduce分别是做什么的？

类中MapReduce的工作原理是什么？map阶段和reduce阶段共同点是什么？

mapreduce 客户端对 map 阶段并行度规划的基本逻辑是怎样的呢？

MapReduce在Map阶段该如何优化方法呢？

共有36条

< 1 2 3 4 >

跳转至： GO

更新时间 2024-02-29 06:26:11

本页面内关键词为智能算法引擎基于机器学习所生成，如有任何问题，可在页面下方点击"联系我们"与我们沟通。

产品推荐

{"moduleinfo":{"card_count":[{"count_phone":1,"count":1}],"search_count":[{"count_phone":3,"count":3}]},"card":[{"des":"E-MapReduce 是构建于阿里云ECS弹性虚拟机之上，利用开源大数据生态系统，包括Hadoop，Spark，Kafka，Storm，为用户提供集群，作业，数据等管理的一站式大数据处理分析业务。","link1":"https://www.aliyun.com/product/emapreduce","link":"https://www.aliyun.com/product/emapreduce","icon":"https://img.alicdn.com/tfs/TB10yI6DNn1gK0jSZKPXXXvUXXa-201-200.png","btn2":"产品文档","tip":"海量存储，离线计算，实时计算场景等各种场景，Hadoop，Spark，Hive，Kafka，Storm等集群快速购买，<a href=\"https://www.aliyun.com/product/emapreduce\" target=\"_blank\">立即查看</a>产品动态发布：<a href=\"https://www.aliyun.com/product/new\" target=\"_blank\">立即查看</a>","btn1":"立即开通","link2":"https://help.aliyun.com/document_detail/28068.html","title":"E-MapReduce"}],"search":[{"txt":"购买建议","link":"https://help.aliyun.com/document_detail/65683.html"},{"txt":"集群规划","link":"https://help.aliyun.com/document_detail/58901.html"},{"txt":"Spark开发入门","link":"https://help.aliyun.com/document_detail/28116.html"},{"txt":"快速入门","link":"https://help.aliyun.com/document_detail/43753.html"},{"txt":"产品动态","link":"https://www.aliyun.com/product/new"}],"countinfo":{"search":{"length_pc":0,"length":0},"card":{"length_pc":0,"length":0}},"simplifiedDisplay":"newEdition","newCard":[{"link":"https://www.aliyun.com/product/emapreduce","icon":"emapreduce","contentLink":"https://www.aliyun.com/product/emapreduce?spm=5176.19720258.J_8058803260.198.4d7a2c4aDND26z","title":"开源大数据平台 E-MapReduce","des":"开源大数据平台 E-MapReduce（简称“EMR”）是云原生开源大数据平台，向客户提供简单易集成的Hadoop、Hive、Spark、Flink、Presto、ClickHouse、StarRocks、Delta、Hudi等开源大数据计算和存储引擎服务。","btn1":"产品控制台","link1":"https://emr-next.console.aliyun.com/","btn2":"立即开通","link2":"https://emr-next.console.aliyun.com/#/create/ecs","btn3":"产品文档","link3":"https://help.aliyun.com/document_detail/28068.html","infoGroup":[{"infoName":"优惠活动","infoContent":{"firstContentName":"StarRocks 免费试用","firstContentLink":"https://free.aliyun.com/?pipCode=emapreduce&spm=5176.28055625.J_4VYgf18xNlTAyFFbOuOQe.118.e939154awRTC1N&scm=20140722.M_9821919._.V_1"}},{"infoName":"产品入门","infoContent":{"firstContentName":"快速入门指导","firstContentLink":"https://help.aliyun.com/document_detail/176795.html?spm=a2c4g.11186623.6.572.68403b8bI3rak8","lastContentName":"常见问题","lastContentLink":"https://help.aliyun.com/document_detail/28186.html?spm=a2c4g.11186623.6.1143.7bce1c52WiJTBt"}},{"infoName":"最佳实践","infoContent":{"firstContentName":"EMR实时计算实践","firstContentLink":"https://help.aliyun.com/document_detail/127198.html?spm=5176.cnemapreduce.0.0.3dd23a1cfXWfSP","lastContentName":"EMR弹性计算实践","lastContentLink":"https://bp.aliyun.com/front/home/detail/36?spm=5176.cnemapreduce.0.0.3dd23a1cfXWfSP"}},{"infoContent":{"lastContentName":"","lastContentLink":"","firstContentName":"产品最新动态","firstContentLink":"https://www.aliyun.com/product/new?category=19&product=125"},"infoName":"最新动态"}],"ifIcon":"icon","iconImg":"https://img.alicdn.com/tfs/TB1XY8hGYr1gK0jSZFDXXb9yVXa-1740-328.png"}]}

{"$env":{"JSON":{}},"$page":{"env":"production"},"$context":{"moduleinfo":{"card_count":[{"count_phone":1,"count":1}],"search_count":[{"count_phone":3,"count":3}]},"card":[{"des":"E-MapReduce 是构建于阿里云ECS弹性虚拟机之上，利用开源大数据生态系统，包括Hadoop，Spark，Kafka，Storm，为用户提供集群，作业，数据等管理的一站式大数据处理分析业务。","link1":"https://www.aliyun.com/product/emapreduce","link":"https://www.aliyun.com/product/emapreduce","icon":"https://img.alicdn.com/tfs/TB10yI6DNn1gK0jSZKPXXXvUXXa-201-200.png","btn2":"产品文档","tip":"海量存储，离线计算，实时计算场景等各种场景，Hadoop，Spark，Hive，Kafka，Storm等集群快速购买，<a href=\"https://www.aliyun.com/product/emapreduce\" target=\"_blank\">立即查看</a>产品动态发布：<a href=\"https://www.aliyun.com/product/new\" target=\"_blank\">立即查看</a>","btn1":"立即开通","link2":"https://help.aliyun.com/document_detail/28068.html","title":"E-MapReduce"}],"search":[{"txt":"购买建议","link":"https://help.aliyun.com/document_detail/65683.html"},{"txt":"集群规划","link":"https://help.aliyun.com/document_detail/58901.html"},{"txt":"Spark开发入门","link":"https://help.aliyun.com/document_detail/28116.html"},{"txt":"快速入门","link":"https://help.aliyun.com/document_detail/43753.html"},{"txt":"产品动态","link":"https://www.aliyun.com/product/new"}],"countinfo":{"search":{"length_pc":0,"length":0},"card":{"length_pc":0,"length":0}},"simplifiedDisplay":"newEdition","newCard":[{"link":"https://www.aliyun.com/product/emapreduce","icon":"emapreduce","contentLink":"https://www.aliyun.com/product/emapreduce?spm=5176.19720258.J_8058803260.198.4d7a2c4aDND26z","title":"开源大数据平台 E-MapReduce","des":"开源大数据平台 E-MapReduce（简称“EMR”）是云原生开源大数据平台，向客户提供简单易集成的Hadoop、Hive、Spark、Flink、Presto、ClickHouse、StarRocks、Delta、Hudi等开源大数据计算和存储引擎服务。","btn1":"产品控制台","link1":"https://emr-next.console.aliyun.com/","btn2":"立即开通","link2":"https://emr-next.console.aliyun.com/#/create/ecs","btn3":"产品文档","link3":"https://help.aliyun.com/document_detail/28068.html","infoGroup":[{"infoName":"优惠活动","infoContent":{"firstContentName":"StarRocks 免费试用","firstContentLink":"https://free.aliyun.com/?pipCode=emapreduce&spm=5176.28055625.J_4VYgf18xNlTAyFFbOuOQe.118.e939154awRTC1N&scm=20140722.M_9821919._.V_1"}},{"infoName":"产品入门","infoContent":{"firstContentName":"快速入门指导","firstContentLink":"https://help.aliyun.com/document_detail/176795.html?spm=a2c4g.11186623.6.572.68403b8bI3rak8","lastContentName":"常见问题","lastContentLink":"https://help.aliyun.com/document_detail/28186.html?spm=a2c4g.11186623.6.1143.7bce1c52WiJTBt"}},{"infoName":"最佳实践","infoContent":{"firstContentName":"EMR实时计算实践","firstContentLink":"https://help.aliyun.com/document_detail/127198.html?spm=5176.cnemapreduce.0.0.3dd23a1cfXWfSP","lastContentName":"EMR弹性计算实践","lastContentLink":"https://bp.aliyun.com/front/home/detail/36?spm=5176.cnemapreduce.0.0.3dd23a1cfXWfSP"}},{"infoContent":{"lastContentName":"","lastContentLink":"","firstContentName":"产品最新动态","firstContentLink":"https://www.aliyun.com/product/new?category=19&product=125"},"infoName":"最新动态"}],"ifIcon":"icon","iconImg":"https://img.alicdn.com/tfs/TB1XY8hGYr1gK0jSZFDXXb9yVXa-1740-328.png"}]}}

开源大数据平台 E-MapReduce

开源大数据平台 E-MapReduce（简称“EMR”）是云原生开源大数据平台，向客户提供简单易集成的Hadoop、Hive、Spark、Flink、Presto、ClickHouse、StarRocks、Delta、Hudi等开源大数据计算和存储引擎服务。

产品控制台

立即开通

产品文档

优惠活动

StarRocks 免费试用

产品入门

快速入门指导

常见问题

最佳实践

EMR实时计算实践