How can I change data in HDFS

Question

How can I change the data of a file that has been stored in hdfs?

Answer 1

You can not modified data once stored in hdfs because hdfs follows Write Once Read Many model. You can only append the data once stored in hdfs.

Comments

We can only append the file which present on hdfs file system for this we follow this method

--to append a file in hdfs first we add the following property in hdfs-site.xml

<property>
  <name>dfs.support.append</name>
  <value>true</value>
  <description> HDFS allow append operation</description></property>

---use the following command for the append operation

hdfs dfs -appendToFile <local_file> /<hdfs_file_name>

EXAMPLE--
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hdfs dfs -appendToFile raj /lok

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Hey. Thanks for the answer. I have another doubt. Suppose I have stored a text file in hdfs. Now I want to append that file and add some more lines. How can I do this?

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I have already mention in above comment full procedure follow that

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I am a little confused. You mentioned that only append is allowed. So when we use the command you mentioned, are the contents of the <local_file> appended to <hdfs_file>?

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At first you add the property in hdfs-site. xml
And after that you use the command