Skip to main content

Hadoop CheatSheet

By

Introduction
We have decided to aggregate in a single post the most important things to know about hadoop in a concise way. Let’s us know if you have any comments!


Hadoop

##########
## HDFS ##
##########

NameNode # => Managing filesystem namespace, if you loose it you have no pointers to your data, you practially lost your data.

DataNode # => You know it holds data, installed on each worker.

Block # => Each file split to B1,B2,.. where each block size 128MB replication is on blocks.  Name node knows that File X is split to B1,B2 and where.

##########
## YARN ##
##########

ResourceManager # => Like `NameNode` for computing, tracks NodeManagers and how available they are for work.

NodeManager # => Like `Datanode` for computing, offer computational resources run applications tasks in containers.

ApplicationMaster # => Each application has `ApplicationMaster` process which negotiates resources with `ResourceManager` which delivers a `container` descriptor back to `ApplicationMaster` processa and asks `NodeManager` to launch the `container.`
 
 ################
 ## Map Reduce ##
 ################
 
 Map(k1, v1) --> list(k2, v2) # => map takes keyvalue pair and produces zero or more intermediate keyvalue pairs
 
 Recduce(k2, list(v2)) --> list(k3, v3) # => Reduce take a single key and list of values and produces zero or more keyvalue, usually aggregation.

Summary

We kept that post small so you could rest :), but in general we went through what NameNode, DataNode, Block, ResourceManager, NodeManager, ApplicationMaster, Task are in a very short and concise way, isn’t that just great :) If you liked it please hit the share button below and leave a comment for any comment! :)




Labels:

Comments

Post a Comment

Popular posts from this blog

Dev OnCall Patterns

By
Introduction Being On-Call is not easy. So does writing software. Being On-Call is not just a magic solution, anyone who has been On-Call can tell you that, it's a stressful, you could be woken up at the middle of the night, and be undress stress, there are way's to mitigate that. White having software developers as On-Calls has its benefits, in order to preserve the benefits you should take special measurements in order to mitigate the stress and lack of sleep missing work-life balance that comes along with it. Many software developers can tell you that even if they were not being contacted the thought of being available 24/7 had its toll on them. But on the contrary a software developer who is an On-Call's gains many insights into troubleshooting, responsibility and deeper understanding of the code that he and his peers wrote. Being an On-Call all has become a natural part of software development. Please note I do not call software development software engineering b
1 comment
Read more

SQL Window functions (OVER, PARTITION_BY, ...)

By
Introduction When you run an SQL Query you select rows, but what if you want to have a summary per multiple rows, for example you want to get the top basketball for each country, in this case we don't only group by country, but we want also to get the top player for each of the country.  This means we want to group by country and then select the first player.  In standard SQL we do this with joining with same table, but we could also use partition by and windowing functions. For each row the window function is computed across the rows that fall into the same partition as the current row.  Window functions are permitted only in the  SELECT  list and the  ORDER BY  clause of the query They are forbidden elsewhere, such as in  GROUP BY ,  HAVING  and  WHERE  clauses. This is because they logically execute after the processing of those clauses Over, Partition By So in order to do a window we need this input: - How do we want to group the data which windows do we want to have? so  def c
Post a Comment
Read more

Functional Programming in Scala for Working Class OOP Java Programmers - Part 1

By
Introduction Have you ever been to a scala conf and told yourself "I have no idea what this guy talks about?" did you look nervously around and see all people smiling saying "yeah that's obvious " only to get you even more nervous? . If so this post is for you, otherwise just skip it, you already know fp in scala ;) This post is optimistic, although I'm going to say functional programming in scala is not easy, our target is to understand it, so bare with me. Let's face the truth functional programmin in scala is difficult if is difficult if you are just another working class programmer coming mainly from java background. If you came from haskell background then hell it's easy. If you come from heavy math background then hell yes it's easy. But if you are a standard working class java backend engineer with previous OOP design background then hell yeah it's difficult. Scala and Design Patterns An interesting point of view on scala, is
33 comments
Read more