Configuring Sqoop with Mysql? - sqoop

Question

I have successfully installed SQOOP now the problem is that how to implement it with RDBMS and how to load data from RDBMS to HDFS using SQOOP.

Answer 1

By Using Sqoop You can Load Data directly to Hive Tables or Store the data in Some target Directory in HDFS
If you Need to copy data from RDBMS into Some directory
sqoop import
--connect ConnectionString
--username username
--password Your_Database_Password {In case no password Do not Specify it}
--table tableName
--col column_name(s) {In case you need to call specific columns}
--target-dir '/tmp/myfolder'
--boundary-query 'Select min,max from table name'
--m 5 {set number of mappers to 5}
--fields-terminated-by ',' {how do you want your data to look in target file}
Boundary Query : This is something you can specify. If you do not specify this , then by default this is run in as an inner query which adds up to a complex query.
If you specify this explicitly then this runs as a normal query and hence the performance is increased.
Also you may want to restrict the number of observation ,say based on column ID, and suppose you need data from ID 1 to 1000. Then using Boundary condition and split-by you will be able to restrict your import data.
--boundary-query "select 0,1000 from employee'
--split-by ID
Split-By : You use Split by on a Sqoop import to specify the column on basis of which split is required. By default,if you do not specify this, sqoop pics up table's primary key as the Split_by column.
Split By picks up data from tables and stores them in different folders based on number of mappers. By Default Number of Mappers are 4.
This may seem unwanted but in case you have a composite primary key or no primary key at all, then sqoop fails to pick up data and may error out.
Note: You may not face any issue if you set the number of mappers to 1. In this case, no split by condition is used since there is only one mapper. So query runs fine. This can be done using
--m 1
If you Need to copy data from RDBMS into Hive Table
sqoop import
--connect ConnectionString
--username username
--password Your_Database_Password {In case no password Do not Specify it}
--table tableName
--boundary-query 'Select min,max from table name'
--m 5 {set number of mappers to 5}
--hive-import
--hive-table serviceorderdb.productinfo
--m 1
Running a query instead of calling entire table itself
sqoop import
--connect ConnectionString
--username username
--password Your_Database_Password
--query 'select name from employees where name like '%s' and $CONDITIONS'
--m 5 {set number of mappers to 5}
--target-dir '/tmp/myfolder'
--fields-terminated-by ',' {how do you want your data to look in target file}
You may see $conditions as extra parameter $CONDITIONS. This is because this time you specified no table and specified a query explicity. When Sqoop runs, it searches for a boundary conditions, which it does not find. Then It Searches for a table and a primary key for applying boundary query which again it will not find. Hence we use $CONDITIONS to explicitly specify that we are not using a query and use default boundry condition from query result.
Checking if your connection is set up properly : For this you can just call list databases and if the you see your data populated then your connection is fine.
$ sqoop list-databases
--connect jdbc:mysql://localhost/
--username root
--password pwd
Connection String for Different Databases :
MYSQL: jdbc:mysql://<hostname>:<port>/<dbname>
jdbc:mysql://127.0.0.1:3306/test_database
Oracle :#//host_name:port_number/service_name
jdbc:oracle:thin:scott/tiger#//myhost:1521/myservicename
You may learn more about sqoop imports from : https://sqoop.apache.org/docs/1.4.1-incubating/SqoopUserGuide.html

Answer 2

By using sqoop import command you can import data from RDBMS to HDFS, Hive and HBase
sqoop import --connect jdbc:mysql://localhost:portnumber/DBName --username root --table emp --password root -m1
By using this command data will be stored in HDFS.

Answer 3

Sample commands to run sqoop import (load data from RDBMS to HDFS):
Postgres
sqoop import --connect jdbc:postgresql://postgresHost/databaseName
--username username --password 123 --table tableName
MySQL
sqoop import --connect jdbc:mysql://mysqlHost/databaseName --username username --password 123 --table tableName
Oracle*
sqoop import --connect jdbc:oracle:thin:#oracleHost:1521/databaseName --username USERNAME --password 123 --table TABLENAME
SQL Server
sqoop import --connect 'jdbc:sqlserver://sqlserverhost:1433;database=dbname;username=<username>;password=<password>' --table tableName
*Sqoop won't find any columns from a table if you don't specify both the username and the table in correct case. Usually, specifying both in uppercase will resolve the issue.
Read the Sqoop User's Guide: https://sqoop.apache.org/docs/1.4.5/SqoopUserGuide.html
I also recommend the Apache Sqoop Cookbook. You will learn how to use import and export tools, do incremental import jobs, save jobs, solve problems with jdbc drivers and much more. http://shop.oreilly.com/product/0636920029519.do