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Questions tagged [writable]

121 questions
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2 answers

Why should a Writable datatype be Mutable?

Why should a Writable datatype be Mutable? What are the advantages of using Text (vs String) as a datatype for Key/Value in Map, Combine, Shuffle or Reduce processes? Thanks & Regards, Raja
Raja
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Write a binary tree in hadoop FS

I need to write a binary tree to HDFS, which i will use to represent a desicion tree. But in order to do that i first need to create a BinaryTreeNode class, which will be the tree node. These are my class attributes: private String name; private…
jojoba
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XAMPP: [ERROR] InnoDB: The innodb_system data file 'ibdata1' must be writable

I wanted to make my own wiki for my own personal use and carry it around on an external drive. I am using Windows 10. I installed XAMPP portable to my external drive and set up MediaWiki yesterday and everything was fine. I turned off my computer…
Anonymous
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1 answer

How do you handle different value types in reducer

I am writing a mapreduce program which has 2 mappers and 1 reducer, I implemented custom Writable Datatypes for each mapper. The Datatype is more or less just a container where the fields are Text / Intwritable values. So Mapper 1 outputs id(Text),…
VSEWHGHP
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Is there a way to modify the code of a function in a Linux C program at runtime?

To be simple, we have two similar functions: void f1() { printf("%d", 123); } void f2() { printf("%d", 124); } Now we call f1 in main and it prints 123. When it is compiled, the disassembly of f1 may be like: 08048424 : 8048424: …
terry
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Extjs store.save() not recognize update

I follow instruction in writer to create grid with CRUD ability, but the problem is when I edit existing row and save() it recognize that dirty row as create, I think the problem may lie in my idProperty as in link, but can't figure out how. Here is…
sarunw
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wdired mode: create, copy, delete files and directories

I know I can move files by renaming them in wdired mode. I am wondering if there is a chance of creating, copying, deleting files/directories in writable dired mode.
Yuki
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ArrayWritable as key in Hadoop MapReduce

I am attempting to create a dynamic map reduce application that takes in dimensions from an external properties file. The main problem lies in the fact that the variables i.e. the key will be composite and may be of whatever numbers, e.g pair of 3…
Pritish Kamath
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1 answer

SetWritable in Hadoop?

I am trying to create a SetWritable in Hadoop. Here is my implementation. I have just started with MapReduce and I can't figure out how exactly I should do this. I wrote the below code but it doesn't work. Custom Writable(which needs to be a…
Aniket Kapse
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1 answer

Hadoop MapReduce chain with ArrayWritable

I'm trying to create a mapreduce chain composed of two steps. The first reduce emit key-value pairs as (key, value) where value is a list of custom object and the second mapper should read the output of the first reducer. The list is a custom…
Fabio Sist
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1 answer

How to serialize very large object in Hadoop Writable

Hadoop Writable interface relies on "public void write(DataOutput out)" method. It looks like behind DataOutput interface, Hadoop uses DataOutputStream, which uses a simple array under the cover. When I try to write a lot of data in DataOutput in my…
user1234883
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Is there a simple way to migrate from SequenceFiles to Avro?

I'm currently using hadoop mapreduce jobs with SequenceFiles of writables. The same Writable type are used for serialization also in the non-hadoop related parts of the system. This method is hard to maintain - mainly because of the lack of schema…
Ophir Yoktan
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writable mount encrypted obb with StorageManager in Android

I need to mount an obb encrypted file writable. Mounting an encrypted obb works just fine but is always readable, so i can't delete files or modify them getApplication().getSM().mountObb(mExpansionFile.getAbsolutePath(), …
user1103419
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What is the reason for having Writable wrapper classes in Hadoop MapReduce for Java types?

It seems to me that a org.apache.hadoop.io.serializer.Serialization could be written to serialize the java types directly in the same format that the wrapper classes serialize the type into. That way the Mappers and Reducers don't have to deal with…
user533020
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Is the directory NOT writable

Can anyone tell me why this is always saying that the directory is not writable, when it absolutely is? $dnam="/home/bryan/renametest/C D" # Is the directory writable err=0 if [ ! -w $dnam ] then # Not writable. Pop the…
user2021539
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