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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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1 answer
81 views

Hadoop, Spark and Cloud

It seems Hadoop, Spark, and different versions of Clouds offer facilities to store and analyze big data. There are some articles comparing Hadoop and Spark (for example, this article). There are also ...
1 vote
2 answers
6k views

how to disable query from beeline results

I am occuring a strange hive-client beeline behavior. In the outputed file with query results there is also a queary at the ...
0 votes
1 answer
297 views

Storage of N-dimensional matrices (tensors) as part of machine learning pipelines

I'm an infra person working on a storage product. I've been googling quite a bit to find an answer to the following question but unable to do so. Hence, I am attemping to ask the question here. I am ...
1 vote
1 answer
334 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 ...
1 vote
0 answers
18 views

what is a data lake catalog technically?

Is a datalake catalog, a file (XML) that the datalake consults before storing retrieving data from a Hadoop database? Thanks.
0 votes
1 answer
36 views

Can I update the source of Data found in a Data Lake or Data Blob

Is it possible to update the source of data found in a Data Lake or Data Blob? What about while using HDInsight or Azure Databricks?
0 votes
1 answer
36 views

What is the difference between Data Modeling and Data Processing?

When discussing big data, it is sometimes mentioned that data modeling can be done by using a tool like map reduce, while data processing may be performed by apache spark. What is the difference ...
40 votes
10 answers
21k views

Do I need to learn Hadoop to be a Data Scientist?

An aspiring data scientist here. I don't know anything about Hadoop, but as I have been reading about Data Science and Big Data, I see a lot of talk about Hadoop. Is it absolutely necessary to learn ...
1 vote
1 answer
40 views

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 ?
6 votes
3 answers
2k views

Is there a benefit to using hadoop with only one node?

I just started learning about Hadoop. From what I understand its primary strength is its ability to distribute a task across many nodes. Is there any benefit to using Hadoop with only a single node, ...
2 votes
2 answers
3k views

Accumulators in Spark (PySpark) without global variables?

BACKGROUND Consider the following textbook example which uses accumulators to add vectors. ...
1 vote
0 answers
115 views

Word count with map reduce

Suppose we use an input file that contains the following lyrics from a famous song: We’re up all night till the sun We’re up all night to get some The input pairs for the Map phase will be the ...
2 votes
1 answer
70 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 ...
5 votes
1 answer
2k 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 ...
2 votes
2 answers
9k views

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 ...
0 votes
1 answer
31 views

Can Single Node Hadoop Cluster be installed on a system with 1gb RAM

I am trying to learn hadoop, would like to know if for basic single node installation 1gb RAM system would be enough or we need more RAM. It would be helpful if someone can share what other minimum ...
0 votes
1 answer
60 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 ...
0 votes
1 answer
202 views

How to run unmodified Python program on GPU servers with scheduled GPUs?

Say I have one server with 10 GPUs. I have a python program which detects available GPU and use all of them. I have a couple of users who will run python (Machine learning or data mining) programs and ...
0 votes
1 answer
23 views

What are common problems around HADOOP storage?

I've been asked to lead a program to understand why our Hadoop storage is constantly near capacity. What questions should I ask? Data age, Data size? Housekeeping schedule? How do we identify the ...
4 votes
1 answer
871 views

What is the main difference between Hadoop and Spark? [closed]

I recently read the following about Hadoop vs. Spark: Insist upon in-memory columnar data querying. This was the killer-feature that let Apache Spark run in seconds the queries that would take Hadoop ...
0 votes
2 answers
1k 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 ...
6 votes
1 answer
3k views

How to make k-means distributed?

After setting up a 2-noded Hadoop cluster, understanding Hadoop and Python and based on this naive implementation, I ended up with this code: ...
0 votes
1 answer
401 views

Hive / Impala best practice code structuring

Coming from a DWH-background I am used to putting subqueries almost everywhere in my queries. On a Hadoop project (with Hive version 1.1.0 on Cloudera), I noticed we can forego subqueries in some ...
34 votes
5 answers
13k views

What are the use cases for Apache Spark vs Hadoop

With Hadoop 2.0 and YARN Hadoop is supposedly no longer tied only map-reduce solutions. With that advancement, what are the use cases for Apache Spark vs Hadoop considering both sit atop of HDFS? I've ...
3 votes
1 answer
547 views

BERT in production

I've created a BERT model. What are the ways to do the deployment of this model? Is it possible to use it with Spark, Hadoop or Docker?
1 vote
0 answers
1k views

cannot access hive from spark [closed]

I am trying to install a hadoop + spark + hive cluster. I am using hadoop 3.1.2, spark 2.4.5 (scala 2.11 prebuilt with user-provided hadoop) and hive 2.3.3 (also tried 3.1.2 with the exact same ...
1 vote
0 answers
40 views

Loading file into and out of HDFS via system call/cmd line vs using libhdfs

I am trying to implement a simple C/C++ program for the HDFS file system like word count, it takes a file from the input path puts it into HDFS (where it gets split), processed my map-reduce function ...
1 vote
0 answers
25 views

Processing XML via StreamXmlRecordReader and Pig in parallel

I'm trying to process a single large XML file with many records and then parse each record in parallel using AWS EMR. ...
2 votes
1 answer
6k views

Are parquet files compressed? [closed]

Parquet File Format Hadoop. Parquet, an open-source file format for Hadoop. Parquet stores nested data structures in a flat columnar format. Compared to a traditional approach where data is stored in ...
1 vote
0 answers
128 views

How to push tasks to remote Hadoop/Spark cluster

I have access to a Hadoop cluster provided by a third party. Currently, I use Spark on this cluster by logging in to a Zeppelin ...
2 votes
0 answers
267 views

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 ...
-1 votes
1 answer
95 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 ...
4 votes
2 answers
100 views

Pig script code error?

While running the below pig script I am getting an error in line4: If it is GROUP then I am getting error. If I change from 'GROUP' TO 'group' in line4, then the script is running. What is the ...
0 votes
1 answer
21 views

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 ...
1 vote
0 answers
715 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 ...
2 votes
0 answers
91 views

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 ...
4 votes
1 answer
404 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 ...
1 vote
0 answers
27 views

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
1 vote
0 answers
133 views

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 ...
3 votes
0 answers
585 views

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

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, ...
0 votes
2 answers
215 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,...
3 votes
1 answer
263 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 ...
2 votes
1 answer
2k views

Error when using MAX in Apache Pig (Hadoop)

I am trying to calculate maximum values for different groups in a relation in Pig. The relation has three columns patientid, featureid and featurevalue (all int). I group the relation based on ...
1 vote
1 answer
161 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 ...
2 votes
1 answer
392 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 ...
0 votes
1 answer
70 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. ...
1 vote
0 answers
111 views

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 ...
1 vote
0 answers
301 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 ...
1 vote
0 answers
386 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 ...
2 votes
1 answer
24 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: ...