sqoop - Sqoop Import - apache sqoop - sqoop tutorial - sqoop hadoop
What is Import in Sqoop?
- We can import data from a relational database system into HDFS. The input to the import process is a database table.
- Sqoop will read the table row-by-row into HDFS. A by-product of the import process is a generated Java class which can encapsulate one row of the imported table.
- All records are stored as text data in the text files or as binary data in Avro and Sequence files.
Syntax:
- The following syntax is used to import data into HDFS.
$ sqoopimport(generic-args)(import-args)
$ sqoop-import(generic-args)(import-args)
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Example:
- Let us take an example of three tables named as emp, emp_add, and emp_contact, which are in a database called userdb in a MySQL database server.
- The three tables and their data are as follows.
emp:
| id | name | deg | salary | dept |
|---|---|---|---|---|
| 1201 | gopal | manager | 50,000 | TP |
| 1202 | manisha | Proof reader | 50,000 | TP |
| 1203 | khalil | php dev | 30,000 | AC |
| 1204 | prasanth | php dev | 30,000 | AC |
| 1204 | kranthi | admin | 20,000 | TP |
emp_add:
| id | hno | street | city |
|---|---|---|---|
| 1201 | 288A | vgiri | jublee |
| 1202 | 108I | aoc | sec-bad |
| 1203 | 144Z | pgutta | hyd |
| 1204 | 78B | old city | sec-bad |
| 1205 | 720X | hitec | sec-bad |
emp_contact:
| id | phno | |
|---|---|---|
| 1201 | 2356742 | [email protected] |
| 1202 | 1661663 | [email protected] |
| 1203 | 8887776 | [email protected] |
| 1204 | 9988774 | [email protected] |
| 1205 | 1231231 | [email protected] |
Importing a Table:
- Sqoop tool ‘import’ is used to import table data from the table to the Hadoop file system as a text file or a binary file.
- The following command is used to import the emp table from MySQL database server to HDFS.
$ sqoopimport \--connect jdbc:mysql://localhost/userdb \--username root \--table emp --m 1
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If it is executed successfully, then you get the following output.
14/12/22 15:24:54 INFO sqoop.Sqoop: Running Sqoop version: 1.4.5
14/12/22 15:24:56 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset.
14/12/22 15:24:56 INFO tool.CodeGenTool: Beginning code generation
14/12/22 15:24:58 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT 1
14/12/22 15:24:58 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT 1
14/12/22 15:24:58 INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /usr/local/hadoop
14/12/22 15:25:11 INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-hadoop/compile/cebe706d23ebb1fd99c1f063ad51ebd7/emp.jar
-----------------------------------------------------
-----------------------------------------------------
14/12/22 15:25:40 INFO mapreduce.Job: The url to track the job: http://localhost:8088/proxy/application_1419242001831_0001/
14/12/22 15:26:45 INFO mapreduce.Job: Job job_1419242001831_0001 running in ubermode : false
14/12/22 15:26:45 INFO mapreduce.Job: map 0% reduce 0%
14/12/22 15:28:08 INFO mapreduce.Job: map 100% reduce 0%
14/12/22 15:28:16 INFO mapreduce.Job: Job job_1419242001831_0001 completed successfully
-----------------------------------------------------
-----------------------------------------------------
14/12/22 15:28:17 INFO mapreduce.ImportJobBase: Transferred 145 bytes in 177.5849 seconds (0.8165 bytes/sec)
14/12/22 15:28:17 INFO mapreduce.ImportJobBase: Retrieved 5 records.
To verify the imported data in HDFS, use the following command.
$ $HADOOP_HOME/bin/hadoop fs -cat /emp/part-m-*Click "Copy code" button to copy into clipboard - By wikitechy - sqoop tutorial - team
- It shows you the emp table data and fields are separated with comma (,).
1201,aadav, php dev,50000, TP1202, mahi,preader,50000, TP1203,charu,manager,50000, AC1204,hena,phpdev,30000, AC1205, leena, admin,20000, TP
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Importing into Target Directory:
- We can specify the target directory while importing table data into HDFS using the Sqoop import tool.
- Following is the syntax to specify the target directory as option to the Sqoop import command.
--target-dir<newor exist directory in HDFS>
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- The following command is used to import emp_add table data into ‘/queryresult’ directory.
$ sqoopimport \--connect jdbc:mysql://localhost/userdb \--username root \--table emp_add \--m 1 \--target-dir/queryresult
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- The following command is used to verify the imported data in /queryresult directory form emp_add table.
$ $HADOOP_HOME/bin/hadoopfs-cat /queryresult/part-m-*
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- It will show you the emp_add table data with comma (,) separated fields.
1201,288A,vgiri, jublee1202,108I,aoc, sec-bad1203,144Z,pgutta, hyd1204,78B,oldcity, sec-bad1205,720C,hitech, sec-bad
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Import Subset of Table Data:
- We can import a subset of a table using the ‘where’ clause in Sqoop import tool.
- It executes the corresponding SQL query in the respective database server and stores the result in a target directory in HDFS.
- The syntax for where clause is as follows.
--where<condition>
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- The following command is used to import a subset of emp_add table data.
- The subset query is to retrieve the employee id and address, who lives in Secunderabad city.
$ sqoop import \--connect jdbc:mysql://localhost/userdb \--username root \--table emp_add \--m 1 \--where“city =’sec-bad’” \--target-dir/wherequery
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- The following command is used to verify the imported data in /wherequery directory from the emp_add table.
$ $HADOOP_HOME/bin/hadoopfs-cat /wherequery/part-m-*
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- It will show you the emp_add table data with comma (,) separated fields.
1202,108I,aoc, sec-bad1204,78B,oldcity, sec-bad1205,720C,hitech, sec-bad
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Incremental Import:
- Incremental import is a technique that imports only the newly added rows in a table.
- It is required to add ‘incremental’, ‘check-column’, and ‘last-value’ options to perform the incremental import.
- The following syntax is used for the incremental option in Sqoop import command.
--incremental <mode>--check-column <column name>--last value <last check column value>
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- Let us assume the newly added data into emp table is as follows:
1206, priya, grp des,10000, GR
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- The following command is used to perform the incremental import in the emptable.
$ sqoop import \--connect jdbc:mysql://localhost/userdb \--username root \--table emp \--m 1 \--incremental append \--check-column id \-last value 1205
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- The following command is used to verify the imported data from emp table to HDFS emp/ directory.
$ $HADOOP_HOME/bin/hadoop fs -cat /emp/part-m-*
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- It shows you the emp table data with comma (,) separated fields.
1201, aadav,php dev,50000, TP1202, mahi, preader,50000, TP1203, charu,manager,30000, AC1204, hena, php dev,30000, AC1205, leena, admin,20000, TP1206, priya , grp des,10000, GRClick "Copy code" button to copy into clipboard - By wikitechy - sqoop tutorial - team
- The following command is used to see the modified or newly added rows from the emp table.
$ $HADOOP_HOME/bin/hadoop fs -cat /emp/part-m-*1
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- It shows you the newly added rows to the emp table with comma (,) separated fields.
1206, priya, grp des,10000, GR