MapReduce

HDFS write resulting in “ CreateSymbolicLink error (1314): A required privilege is not held by the client.”

由 旧街凉风 提交于 2019-12-07 05:49:21
问题 Tried to execute sample map reduce program from Apache Hadoop. Got exception below when map reduce job was running. Tried hdfs dfs -chmod 777 / but that didn't fix the issue. 15/03/10 13:13:10 WARN mapreduce.JobSubmitter: Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this. 15/03/10 13:13:10 WARN mapreduce.JobSubmitter: No job jar file set. User classes may not be found. See Job or Job#setJar(String). 15/03

How to have lzo compression in hadoop mapreduce?

由 邮差的信 提交于 2019-12-07 05:32:25
I want to use lzo to compress map output but I can't run it! The version of Hadoop I used is 0.20.2 . I set: conf.set("mapred.compress.map.output", "true") conf.set("mapred.map.output.compression.codec", "org.apache.hadoop.io.compress.LzoCodec"); When I run the jar file in Hadoop it shows an exception that can't write map output. Do I have to install lzo? What do I have to do to use lzo? LZO's licence (GPL) is incompatible with that of Hadoop (Apache) and therefore it cannot be bundled with it. One needs to install LZO separately on the cluster. The following steps are tested on Cloudera's

is the output of map phase of the mapreduce job always sorted?

由 |▌冷眼眸甩不掉的悲伤 提交于 2019-12-07 05:19:45
问题 I am a bit confused with the output I get from Mapper. For example, when I run a simple wordcount program, with this input text: hello world Hadoop programming mapreduce wordcount lets see if this works 12345678 hello world mapreduce wordcount this is the output that I get: 12345678 1 Hadoop 1 hello 1 hello 1 if 1 lets 1 mapreduce 1 mapreduce 1 programming 1 see 1 this 1 wordcount 1 wordcount 1 works 1 world 1 world 1 As you can see, the output from mapper is already sorted. I did not run

Get the sysdate -1 in Hive

由 妖精的绣舞 提交于 2019-12-07 05:06:02
问题 Is there any way to get the current date -1 in Hive means yesterdays date always? And in this format- 20120805 ? I can run my query like this to get the data for yesterday's date as today is Aug 6th - select * from table1 where dt = '20120805'; But when I tried doing this way with date_sub function to get the yesterday's date as the below table is partitioned on date(dt) column. select * from table1 where dt = date_sub(TO_DATE(FROM_UNIXTIME(UNIX_TIMESTAMP(), 'yyyyMMdd')) , 1) limit 10; It is

loading 1GB data into hbase taking 1 hour

由 穿精又带淫゛_ 提交于 2019-12-07 04:54:35
问题 I want to load 1GB (10 Million Records) CSV file into Hbase. I wrote Map-Reduce Program for it. My Code is working fine but taking 1 hour to complete. Last Reducer is taking more than half an hour time. Could anyone please help me out? My Code is as follows: Driver.Java package com.cloudera.examples.hbase.bulkimport; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.KeyValue; import

Identifying Duplicates in CouchDB

由 徘徊边缘 提交于 2019-12-07 04:37:31
问题 I'm new to CouchDB and document-oriented databases in general. I've been playing around with CouchDB, and was able to get familiar with creating documents (with perl) and using the Map/Reduce functions in Futon to query the data and create views. One of the things I'm still trying to figure out is how to identify duplicate values across documents using Futon's Map/Reduce. For example, if I have the following documents: { "_id": "123", "name": "carl", "timestamp": "2012-01-27T17:06:03Z" } { "

Why is Spark not using all cores on local machine

由 浪子不回头ぞ 提交于 2019-12-07 04:30:32
问题 When I run some of the Apache Spark examples in the Spark-Shell or as a job, I am not able to achieve full core utilization on a single machine. For example: var textColumn = sc.textFile("/home/someuser/largefile.txt").cache() var distinctWordCount = textColumn.flatMap(line => line.split('\0')) .map(word => (word, 1)) .reduceByKey(_+_) .count() When running this script, I mostly see only 1 or 2 active cores on my 8 core machine. Isn't Spark supposed to parallelise this? 回答1: You can use local

java.lang.IllegalArgumentException: Wrong FS: , expected: hdfs://localhost:9000

由 匆匆过客 提交于 2019-12-07 04:27:42
问题 I am trying to implement reduce side join , and using mapfile reader to look up distributed cache but it is not looking up the values when checked in stderr it showed the following error, lookupfile file is already present in hdfs , and seems to be loaded correctly into cache as seen in the stdout. java.lang.IllegalArgumentException: Wrong FS: file:/app/hadoop/tmp/mapred/local/taskTracker/distcache/-8118663285704962921_-1196516983_170706299/localhost/input/delivery_status/DeliveryStatusCodes

ZeroCopyLiteralByteString cannot access superclass

由 和自甴很熟 提交于 2019-12-07 04:00:31
问题描述 在HBase上运行MapReduce作业时，报如下异常：IllegalAccessError: class com.google.protobuf.HBaseZeroCopyByteString cannot access its superclass com.google.protobuf.LiteralByteString 使用HBase环境如下：CDH5.0.1, HBase版本：0.96.1 问题原因 This isssue occurs because of an optimization introduced in HBASE-9867 that inadvertently introduced a classloader dependency. This affects both jobs using the -libjars option and "fat jar," jobs which package their runtime dependencies in a nested lib folder. 这个问题的发生是由于优化了 HBASE-9867 引起的，无意间引进了一个依赖类加载器。它影响使用-libjars参数和使用 fat jar两种模式的job. fat jar模式Hadoop的一个特殊功能：可以读取操作目录中

Riak fails at MapReduce queries. Which configuration to use?

由 江枫思渺然 提交于 2019-12-07 02:04:06
问题 I am working on a nodejs application in combination with riak / riak-js and run into the following problem: Running this request db.mapreduce .add('logs') .run(); corretly returns all 155.000 items stored in the bucket logs with their IDs: [ 'logs', '1GXtBX2LvXpcPeeR89IuipRUFmB' ], [ 'logs', '63vL86NZ96JptsHifW8JDgRjiCv' ], [ 'logs', 'NfseTamulBjwVOenbeWoMSNRZnr' ], [ 'logs', 'VzNouzHc7B7bSzvNeI1xoQ5ih8J' ], [ 'logs', 'UBM1IDcbZkMW4iRWdvo4W7zp6dc' ], [ 'logs', 'FtNhPxaay4XI9qfh4Cf9LFO1Oai' ],
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