Importing data from postgres tables into HDFS using sqoop could be done with the following steps.
Make sure postgres jdbc connector is available in /usr/share/java
directory.
To list all available tables in the postgres database
$ sqoop list-tables \
--connect jdbc:postgresql://hostname.com/databaseName \
--username myUserName \
--password myPassword
To import table to HDFS
$ sqoop import \
--connect jdbc:postgresql://hostname.com/databaseName \
--username myUserName \
--password myPassword \
--table myTableName
--columns "col_1,col_2"
-m 1 \
--target-dir /user/hue/myTableName \
--enclosed-by '\"'
After successfull completion of the above command, the imported file should be available in the target-dir /user/hue/myTableName/part-m-00000
This file can be used to create HCatalog table for querying with Hive or Pig.
I'm using Hortonworks HDPv2.1.1 in AWS EC2.
This is a simple usecase of using sqoop. Hope this helps.