What is Pig?.Why Pig? How to use Pig.Is it similar to Hive? How to write scripts in Pig?

1. Prepared by : Abhishek Gautam

2.  It is a part of Hadoop ecosystem which is used to process
large datasets.
 Used to automate ETL for unstructured data.
 It’s a procedural language.
 Used by both Data analyst & developers.
 The language used here is called Pig Latin.
 Pig relations are non-persistent across sessions.

3.  Local Mode :
 In Local Mode of Pig execution, all the input data will be
taken from local file system. After execution it provides
output on top of local file system.
 This mode of suitable only for small datasets and when
trying out Pig.
 To start the local mode of execution, the following command
is used. pig -x local

4.  Mapreduce Mode :
 In this mode Apache Pig will take the input form HDFS paths
only, and after processing data it will put output files on top
of HDFS.
 In MapReduce mode of execution, Pig translates queries into
MapReduce jobs and runs them on a Hadoop Cluster.
 This is the default mode of execution.
 To start the Mapreduce mode of execution, the following
command is used. pig -x mapreduce

5.  Tez Mode :
 Tez mode is more flexible and faster than Mapreduce mode
but lack some performance issues.
 To run Pig inTez mode, you need access to a Hadoop cluster
and HDFS installation.
 To start the tez mode of execution, the following command
is used. pig -x tez

6.  Use the LOAD operator to load the data into a table.
 Use the STORE operator to store the data into another
location.
 Use the DUMP operator to display results to your terminal
screen.
 Use the DESCRIBE operator to review the schema of a
relation.

7.  While Loading data into a table if column name is not
specified in a table then we can name the columns from
starting as $0, $1,$2….