Questions tagged [apache-hadoop]

Hadoop is an Apache open-source project that provides software for reliable and scalable distributed computing. The project itself includes a variety of other complementary additions.

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how to run pyspark on Hadoop cluster, cache data, then read file using pandas on local machine via its URI?

I connect to a Hadoop cluster via vpn. I want to execute a script that makes sql call and saves the data to a file on the remote machine, then using its URI I want to read on my local running Jupiter ...
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How to create tensors in spark?

I have the following data stored in HDFS: each row has three columns, id, date, item, which means a person with a particular id bought a particular item on a particular date. The dataset has billions ...
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27 views

Mapreduce jobs not working in hive

I was trying to execute a query select name, count(*) from amazon where review != NULL group by name ; Number of reduce tasks not specified. Estimated ...
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21 views

Confused about testing graph

I am doing an image classification project using CNN (convolution neural network) model. I have plotted a training and validation graph. I was asked to plot a testing graph. I don’t know about testing ...
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38 views

What is the MapReduce application master?

From Hadoop The Definitive Guide The whole process is illustrated in Figure 7-1. At the highest level, there are five independent entities: • The client, which submits the MapReduce ...
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is there a step where replicated data across different Hadoop nodes “synchronize” when job done

assume there are 3 Hadoop nodes have the same 50MB file block and doing a word count job. is there a step where that 3 nodes does the job separately and "synchronize" the result when job done?
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what does “blocks” mean in the context of HDFS ecosystem? is it the same concept in the context of a single hard disk drive?

According to Hortonworks HDFS has demonstrated production scalability of up to 200 PB of storage and a single cluster of 4500 servers, supporting close to a billion files and blocks. what does ...
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Hints on my EMR Spark Cluster

I am new to Spark, in particular I am tying to find out which are the best recommended properties to set to work on a 1 master 2 slaves cluster with 10GB memory each. Do you know which are a good set ...
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210 views

Datanode not starting on Slave Nodes for Apache Hadoop+Spark Setup

I know similar questions have been asked and I already looked through a lot of them to figure out what the issue might be, but to no avail. I am a College student currently working on a Big Data ...
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1answer
41 views

SAP HANA or Hadoop? [closed]

this is a question regarding a career choice. I am a fresher and I recently joined an MNC in Data Engineering team. There I was offered training in either Hadoop or SAP HANA. I am in doubt as to which ...
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161 views

Is there any point in learning Hadoop in 2018?

I'm a data analyst/scientist working mostly with the Python open source stack i.e. Pandas, scikit-learn, matplotlib, seaborn etc. I want to expand my toolbox and learn a distributed computing ...
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877 views

Accumulators in Spark (PySpark) without global variables?

BACKGROUND Consider the following textbook example which uses accumulators to add vectors. ...
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PySpark: java.io.EOFException

System: 1 name node, 4 cores, 16 GB RAM 1 master node, 4 cores, 16 GB RAM 6 data nodes, 4 cores, 16 GB RAM each 6 worker nodes, 4 cores, 16 GB RAM each around 5 Terabytes of storage space The data ...
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Remote sensing image data storage in hadoop hdfs [closed]

I am new to hadoop environment. anyone kindly please help me how to store the remote sensing image data in hadoop hdfs? thanks in advance
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Unable to open application master UI in spark1.6.1 in cluster mode

Hadoop cluster has 8 nodes with high availability of resource manager. Active ResourceManager is in node 3. and Standby ResourceManager in node 2. when i submit the application in cluster mode. the ...
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397 views

Communication between name node, data node and client in hadoop by analysing Packet Capturing

if I say that in hadoop cluster system... A client has 10GB data to send to name node. After analysing the "packet capturing" actually the name node doesn't divide the data for data node, ...
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80 views

Change log level of yarn?

I'd like to change the log level of yarn. For example, when I run yarn node -list, I see a line that says ...
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2answers
124 views

Are Hadoop and Python SciPy used for the same? [closed]

Right now I've been doing a bit of research because I'm quite new to Big Data world. Among several other tools or frameworks, I've read about Apache Hadoop and Python for data analysis. Specifically,...
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1answer
40 views

does storing file in hdfs parallelize it for Spark?

For Spark's RDD operations, data must be in shape of RDD or be parallelized using: ParallelizedData = sc.parallelize(data) My question is that if I store data in ...
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1answer
296 views

Best practice for developing using Spark [closed]

I am looking for any tips and best practice on how to develop applications using Spark. I currently have access to a cluster, with data as well as a version of Spark 2.1.0 on an edge node and IntelliJ ...
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1answer
983 views

Saving Large Spark ML Pipeline to HDFS

I'm having trouble saving a large (relative to spark.rpc.message.maxSize) Spark ML pipeline to HDFS. Specifically, when I try to save the model to HDFS, it gives me an error related to spark's maximum ...
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1answer
52 views

Which one of these tasks will benefit the most from SPARK?

My company processes Data (I am only an intern). We primarily use Hadoop. We're starting to deploy spark in production. Currently we have have two jobs, we will choose just one to begin with spark. ...
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Tasks of a Yarn Process in Hadoop

I am new to big data and Apache Hadoop YARN. This picture show how Yarn runs applications: A client requests a Yarn Application. So, in a certain datanode a Container is created and the process is ...
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Hdfs Data Balance on Cluster

Im new to Big Data, so please just dont blast me. Can you explain me why HDFS works best when the file blocks are evenly spread across the cluster ?
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279 views

Hadoop - checksum while reading file from client [closed]

In hadoop , if i want to read a file from client , the class DFSInputStream enters in action. About this, my textbook says The DFSInputStream also verifies checksums for the data transferred to it ...
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316 views

Custom Writable Serialization in Hadoop [closed]

I have some questions about Custom Writable objects in Hadoop. First of all, the private instance variables of the Writable object have to be Writable? How does Hadoop handle ...
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1answer
19 views

Yarn service parameter for pseudodistributed [closed]

I'm trying to set up Hadoop in the pseudodistributed form. So I edited the suggested xml files. In the file yarn-site.xml, I had to insert: ...
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1answer
44 views

Hadoop and input informations divided in splits [closed]

Hadoop divides the input to a MapReduce job into fixed-size pieces called input splits, or just splits. Hadoop creates one map task for each split, which runs the user-defined map function for ...
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Why does my master node get heap memory full for inbuilt SVD API in Apache Spark during calculation of inverse of a square matrix?

I am using a three node system: Master node: $64$ GB RAM 2 slave node: $32$ GB RAM I am calculating the inverse of a square matrix using inbuilt Apache Spark function SVD. When I called SVD function ...
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1answer
95 views

Install Spark and Hadoop in the same machine [closed]

I'm trying to install Spark Apache and Hadoop in the same machine. Spark will be used to process data, and HDFS from Hadoop will be used to store data. I first started by installing spark and it ...
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279 views

Hadoop Cluster Capacity Planning [closed]

I was doing some digging to get some deeper understanding on the Capacity Planning done for setting up a Hadoop Cluster. I have a daily ~100 GB of data generated and would like to find how a Capacity ...
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213 views

How to setup a home-laptop cluster to 'practice' elasticsearch, hadoop, mesos and spark [closed]

I'd like to have elasticsearch, hadoop, mesos and spark on my home laptop (it's an 8GB with an intel i7 CPU) for practicing the setup of such frameworks and eventually to test their functions. I'm ...
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2answers
593 views

Why has Hadoop failed to become popular?

Apache Hadoop was once considered one of the tools you should have as a Data Scientist. Around 2012 to 2014, it gained the popularity steeply among Data Scientists, and seemed to be considered one of ...
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Are jobs the only way out for data scientists? [closed]

I have reached this point in my data sceince journey that I am left wondering if jobs are the only way out for me... I am highly skilled in Hadoop, Machine Learning and now getting into Deep Learning ...
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1answer
77 views

what ETL technique should i use for text documents using Hadoop?

I have a school Big Data project where basically the teacher is going to give us a large amount of text documents (from the Gutenberg project data set ) and he want us to give as output the document ...
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2answers
333 views

Can R + Hadoop overcome R's memory constraints in any case?

I am an R user and I am interested in learning/understanding how Hadoop actually works. For this I previously read about Hadoop but was not able to find a satisfactory answer for my question. Can R + ...
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1answer
128 views

Deploying models on bigdata platforms like Hadoop and Spark

Where exactly bigdata platforms fit in to a data science/ machine learning projects ? Say I have a large dataset for a binary classification problem - cats and dogs. Now I need to create a model for ...
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1answer
866 views

Ingestion of periodic REST API Calls into Hadoop [closed]

We are planning to use REST API calls to ingest data from an endpoint and store the data to HDFS. The REST calls are done in a periodic fashion (daily or maybe hourly). I've already done Twitter ...
2
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1answer
181 views

K-means clustering on big data stored on multiple nodes on HDFS

I have a very basic question about how the k-means clustering algorithm works when the data is stored in HDFS. Does the training take place on the subset of data on each node for a fixed value of K( ...
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2answers
108 views

How many people can use a single Hadoop cluster at one time?

I would like to know how many people can use a single Hadoop cluster at one time? I am asking because I need to figure out whether or not a single 5 or 10 node cluster would be sufficient to host a ...
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1answer
197 views

Does a big data virtual machine machine help in analyzing large file?

I have a csv file of size 2.5GB. I can not analyze the data of the file in chunks. I don’t have access to a hadoop cluster. But, does running a virtual machine like hortonworks solve my problem? Is ...
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1answer
289 views

Mahout Spark shell not working

I installed Hadoop, Mahout and Spark. I am able to see the Hadoop and Spark MasterWebUI. Moreover, I can also run the following command, ...
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2answers
4k views

spark item similarity recommendation

I would like to build an recommendation engine using spark's Mlib itemsimilarity as mentioned here LINK But it seems spark do not have this algorithm any more and ...
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1answer
175 views

How to Scaling Out Artifical Neural Networks?

I have started to study ANNs with Tensorflow and Keras. Now I want to find a solution to use ANNs over Hadoop. I have learnt that Spark 2.0 does have a Multilayer Perceptron Classifier, but as far as ...
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1answer
84 views

Connecting Twitter API to a Big Data Environment?

I am trying to get live twitter data and store it in a Hadoop environment. Currently, I am learning how to push the data into a Cloudera environment and process it. My questions are: Is Cloudera ...
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1answer
784 views

Machine Learning model to find items that are frequently bought together using Hadoop Spark

I need to do my master thesis under Big Data Analytics - Machine Learning subject. I was challenged to create a Market Basket Analysis project on retail industry. My dataset contains transactions of ...
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1answer
222 views

Spark algorithm to make a link analysis

I'm doing my master thesis on Big Data Analytics. I'm trying to develop a algorithm to identify associations between some products in a supermakert. Imagine that I've this dataset: ...
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8answers
555 views

Skills that school doesn't teach you

I'll be graduating soon with a master's degree in electrical engineering. I have a lot of experience with the theoretical side of machine learning through courses and research, but all of my ...
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266 views

Predictive Analytics on distributed systems vs standalone system

I have somewhat philosophical question regarding performing predictive analytics on distributed systems (such as hadoop). I am no expert on this subject so maybe other folks who have more advance ...
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111 views

How to multiply a “fat and short” matrix with a “tall and thin” matrix using MapReduce?

Assume that $A_{m \times n}$ and $B_{n \times k}$ are to be multiplied to get $C_{m \times k}$. Now if $n$ is too large for a single row $A_{j}$ of $A$ to fit in RAM (and similarly for columns of B) ...