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Help Center/ MapReduce Service/ Component Operation Guide (ME-Abu Dhabi Region)/ Using Loader/ Exporting Data/ Typical Scenario: Exporting Data from Hive to a Relational Database

Typical Scenario: Exporting Data from Hive to a Relational Database

Updated on 2024-07-19 GMT+08:00

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Scenario

Use Loader to export data from Hive to a relational database.

Prerequisites

You have obtained the service username and password for creating a Loader job.
You have had the permission to access the Hive tables that are used during job execution.
You have obtained the username and password of the relational database.
No disk space alarm is reported, and the available disk space is sufficient for importing and exporting data.
If a configured task requires the Yarn queue function, the user must be authorized with related Yarn queue permission.
The user who configures a task must obtain execution permission on the task and obtain usage permission on the related connection of the task.
Before the operation, perform the following steps:
1. Obtain the JAR package of the relational database driver and save it to the following directory on the active and standby Loader nodes: ${BIGDATA_HOME}/FusionInsight_Porter_8.1.0.1/install/FusionInsight-Sqoop-1.99.3/FusionInsight-Sqoop-1.99.3/server/webapps/loader/WEB-INF/ext-lib.
2. Run the following command on the active and standby nodes as user root to modify the permission:
  cd ${BIGDATA_HOME}/FusionInsight_Porter_8.1.0.1/install/FusionInsight-Sqoop-1.99.3/FusionInsight-Sqoop-1.99.3/server/webapps/loader/WEB-INF/ext-lib
  
  chown omm:wheel JAR package name
  
  chmod 600 JAR package name
3. Log in to FusionInsight Manager. Choose Cluster > Name of the desired cluster > Service > Loader > More > Restart. Enter the password of the administrator to restart the Loader service.

Procedure

Setting Basic Job Information

Access the Loader web UI.
1. Log in to FusionInsight Manager. For details, see Accessing FusionInsight Manager (MRS 3.x or Later).
2. Choose Cluster > Name of the desired cluster > Services > Loader.
3. Click LoaderServer(Node name, Active). The Loader web UI is displayed.
  Figure 1 Loader web UI
Click New Job to go to the Basic Information page and set basic job information.

Figure 2 Basic Information
1. Set Name to the name of the job.
2. Set Type to Export.
3. Set Group to the group to which the job belongs. No group is created by default. You need to click Add to create a group and click OK to save the created group.
4. Set Queue to the Yarn queue that executes the job. The default value is root.default.
5. Set Priority to the priority of the Yarn queue that executes the job. The default value is NORMAL. The options are VERY_LOW, LOW, NORMAL, HIGH, and VERY_HIGH.

In the Connection area, click Add to create a connection, set Connector to generic-jdbc-connector or dedicated database connector (oracle-connector, oracle-partition-connector or mysql-fastpath-connector), set connection parameters, and click Test to verify whether the connection is available. When "Test Success" is displayed, click OK.

NOTE:

For connection to relational databases, general database connectors (generic-jdbc-connector) or dedicated database connectors (oracle-connector, oracle-partition-connector, and mysql-fastpath-connector) are available. However, compared with general database connectors, dedicated database connectors perform better in data import and export because they are optimized for specific database types.
When mysql-fastpath-connector is used, the mysqldump and mysqlimport commands of MySQL must be available on NodeManagers, and the MySQL client version to which the two commands belong must be compatible with the MySQL server version. If the two commands are unavailable or the versions are incompatible, see http://dev.mysql.com/doc/refman/5.7/en/linux-installation-rpm.html. Install the MySQL client applications and tools.

**Table 1** **generic-jdbc-connector** connection parameters
Parameter	Description	Example Value
Name	Specifies the name of a relational database connection.	dbName
JDBC Driver Class	Specifies the name of a Java database connectivity (JDBC) driver class.	oracle.jdbc.driver.OracleDriver
JDBC Connection String	Specifies the JDBC connection string.	jdbc:oracle:thin:@//10.16.0.1:1521/oradb
Username	Specifies the username for connecting to the database.	omm
Password	Specifies the password for connecting to the database.	xxxx
JDBC Connection Properties	JDBC connection attribute. Click Add to manually add the attribute. Name: connection attribute name Value: connection attribute value	Name: socketTimeout Value: 20

Setting Data Source Information

Click Next. On the displayed From page, set Source type to HIVE.

**Table 2** Data source parameters
Parameter	Description	Example Value
Hive instance	Specifies the Hive service instance that Loader selects from all available Hive service instances in the cluster. If the selected Hive service instance is not added to the cluster, the Hive job cannot run properly.	hive
Quantity	Specifies the number of maps that are started at the same time in a MapReduce job of a data configuration operation. The value must be less than or equal to 3000.	20

Setting Data Transformation

Click Next. On the displayed Transform page, set the transformation operations in the data transformation process. For details about how to select operators and set parameters, see Operator Help and Table 3.

**Table 3** Setting the input and output parameters of the operator
Input Type	Export Type
Hive input	Table output

Figure 3 Operator operation procedure
Click to enlarge

Setting Data Storage Information and Executing the Job

Click Next. On the displayed To page, set the data storage mode.

**Table 4** Parameter description
Parameter	Description	Example Value
Schema name	Specifies the database schema name.	dbo
Table name	Specifies the name of a database table that is used to save the final data of the transmission. NOTE: Table names can be defined using macros. For details, see Using Macro Definitions in Configuration Items.	test
Temporary table	Specifies the name of a temporary database table that is used to save temporary data during the transmission. The fields in the table must be the same as those in the database specified by Table name. NOTE: A temporary table is used to prevent dirty data from being generated in the destination table when data is exported to the database. Data is migrated from the temporary table to the destination table only after all data is successfully written to the temporary table. Using temporary tables increases the job execution time.	tmp_test

Click Save and run to save and run the job.

Checking the Job Execution Result
Go to the Loader WebUI. When Status is Succeeded, the job is complete.

Figure 4 Viewing a job

Parent topic: Exporting Data

Previous topic: Typical Scenario: Exporting Data from HBase to a Relational Database

Next topic: Typical Scenario: Importing Data from HBase to HDFS or OBS

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