Sunday, April 30, 2017

What are differences between RDBMS and MapReduce


Greeting everyone you will be looking around What is difference between RDBMS and MapReduce. hadoopquiz present here a clear difference.
Many of us usually get confuse while specifying difference between RDBMS and MapReduce.
Below table clearly specifies about this difference hope this will be useful for you.
more differences related to hadoop ecosystem can be find @ Difference Zone

RDBMS stand for Relational Database Management Systems.
Please find below the differences
 Traditional RDBMSMapReduce
Data sizeGigabytesPetabytes
AccessInteractive and batchBatch
UpdatesRead and write many timesWrite once, read many times
Transactions ACIDNone
StructureSchema-on-writeSchema-on-read
IntegrityHighLow
ScalingNonlinearLinear
Reference: Hadoop Definative guide 4th Edition
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Friday, April 21, 2017

What is difference between put and copyfromlocal



Greeting everyone you will be looking around what are the difference between put and copyfromlocal. hadoopquiz present here a clear difference

Many of us usually get confuse while specifying difference between put and copyfromlocal.
Below table clearly specifies about this difference hope this will be usefull for you.
more differences related to hadoop ecosystem can be find @  Difference Zone


       put
           copyFromLocal
Usage
Usage: hdfs dfs -put < localsrc > … < dst >
hadoop fs -copyFromLocal<localsrc> URI
Functionality 1
Put ; Copy single src, or multiple srcs from local file system to the destinationfilesystem
copyFromLocal is similar to put command, except that the source is restricted to a local file reference.
Functionality 2
copy data from local system to HDFS
copy data from local system to HDFS
File Copying Specification
Single file copy: hadoop fs -put localfile/user/hadoop/hdfile

Multiple file copy : hadoopfs -put localfile1 localfile2 /user/hadoop/hddir

copyFromLocal seems to copy a single one file path
Stdin Support
support reading from stdin
does not support reading from stdin
  
Source Code for the same from Hadoop trunk
 
class CopyCommands {  
  public static void registerCommands(CommandFactory factory) {
    factory.addClass(Merge.class"-getmerge");
    factory.addClass(Cp.class"-cp");
    factory.addClass(CopyFromLocal.class"-copyFromLocal");
    factory.addClass(CopyToLocal.class"-copyToLocal");
    factory.addClass(Get.class"-get");
    factory.addClass(Put.class"-put");
  }
  public static class Put extends CommandWithDestination {
    public static final String NAME = "put";
    public static final String USAGE = "<localsrc> ... <dst>";
    public static final String DESCRIPTION =
      "Copy files from the local file system\n" +
      "into fs.";
    ...
  }
  public static class CopyFromLocal extends Put {
    public static final String NAME = "copyFromLocal";
    public static final String USAGE = Put.USAGE;
    public static final String DESCRIPTION = "Identical to the -put command.";
  }
}
a good reply related to difference between put and copyfromlocal is mentioned over stackoverflow.

Let's make an example: If your HDFS contains the path: /tmp/dir/abc.txt 
And if your local disk also contains this path then the hdfs API won't know which one you mean, unless you specify a scheme like file:// or hdfs://. 
Maybe it picks the path you did not want to copy.
Therefore you have -copyFromLocal which is preventing you from accidentally copying the wrong file, by limiting the parameter you give to the local filesystem.
Put is for more advanced users who know which scheme to put in front.

It is always a bit confusing to new Hadoop users which filesystem they are currently in and where their files actually are.

few more differences you can check below
Hadoop Difference Zone


Sr No
Difference Index
Link
1
What is difference between Operational vs. Analytical Systems
2
What is difference between RDBMS vs Hive
3
What is difference between RDBMS vs Hive vs Impala










if you want to add few many things please do comment in comment section.



Wednesday, April 5, 2017

Whats happen in ONE MINUTE over internet search

A statistical analysis of ONE MINUTE internet search.

 Google receives over 2,000,000 search queries.

 Facebook receive 34,722 “likes”.

 Consumers spend $ 272,070 on web shopping.

 Apple receives 47,000 Apps downloads.

 370,00 minutes of calls on Skype,

 98,000 posts on tweets,

 20,000 posts on Tumblr,

 13,000 hours of music streaming on Pandora,

 12,000 new ads on Craigslist,

 6,600 pictures uploaded to Flickr,

 1,500 new blog posts,

 600 new YouTube videos.


One minute

A statistical analysis of One Second in internet search.
Now In One Second:

 7,567 Tweets sent

 59,614Google searches

 774Instagram photos uploaded

 1,227Tumblr posts

 2,530Skype calls

 43,446GB of Internet traffic

 59,614Google searches

 68,756YouTube videos viewed

 2,578,145Emails sent  (67% of them are SPAM)

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