sqoop - Sqoop Eval - apache sqoop - sqoop tutorial - sqoop hadoop
What is Sqoop Eval?
- Sqoop eval tool can be applicable for both modeling and defining the SQL statements.
- It allows users to execute user-defined queries against respective database servers and preview the result in the console.
- So, the user can expect the resultant table data to import.
- Using eval, we can evaluate any type of SQL query that can be either DDL or DML statement.
Syntax
- The following syntax is used for Sqoop eval command.
$ sqoop eval (generic-args) (eval-args)
$ sqoop-eval (generic-args) (eval-args)
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Sqoop Eval Command With Example
- The sqoop eval command describes how to use the Sqoop 'eval' tool.
- It allows users to execute user-defined queries against respective database servers and preview the result in the console.
- So, the user can expect the resultant table data to import. Using eval, we can evaluate any type of SQL query that can be either DDL or DML statement.
Step 1 - Change the directory to /usr/local/hadoop/sbin
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Step 2 - Start all hadoop daemons.
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Step 3 - The JPS (Java Virtual Machine Process Status Tool) tool is limited to reporting information on JVMs for which it has the access permissions
$ jps
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Step 4 - Change the directory to /usr/local/sqoop/bin
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Select Query Evaluation
- Using eval tool, we can evaluate any type of SQL query. Let us take an example of selecting limited rows in the wikitechy_employee table of db database.
- The below command is used to evaluate the given example using SQL query.
$ sqoop eval \
--connect jdbc:mysql://localhost/db \
--username root \
--query “SELECT * FROM wikitechy_employee LIMIT 3”
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- After the execution of the command successfully, then it will produce the below output on the terminal.
+------+--------------+-------------+-------------------+--------+
| Id | Name | Designation | Salary | Dept |
+------+--------------+-------------+-------------------+--------+
| 1201 | venkat | manager | 50000 | TP |
| 1202 | manisha | preader | 50000 | TP |
| 1203 | nila | php dev | 30000 | AC |
+------+--------------+-------------+-------------------+--------+
Insert Query Evaluation
- Sqoop eval tool can be applicable for both modeling and defining the SQL statements.
- That means, we can use eval for insert statements too.
- Using the below command to insert a new row in the wikitechy_employee table of db database.
$ sqoop eval \
--connect jdbc:mysql://localhost/db \
--username root \
-e “INSERT INTO wikitechy_employee VALUES(1207,‘Raju’,‘UI dev’,15000,‘TP’)”
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- After the execution of the command successfully, then it will display the status of the updated rows on the console.
- Otherwise, you can verify the wikitechy_employee table on MySQL console.
- Using the below command to verify the rows of wikitechy_employee table of db database using select’ query.
mysql>
mysql> use db;
mysql> SELECT * FROM wikitechy_employee;
+------+--------------+-------------+-------------------+--------+
| Id | Name | Designation | Salary | Dept |
+------+--------------+-------------+-------------------+--------+
| 1201 | venkat | manager | 50000 | TP |
| 1202 | manisha | preader | 50000 | TP |
| 1203 | nila | php dev | 30000 | AC |
| 1204 | prasanth | php dev | 30000 | AC |
| 1205 | kranthi | admin | 20000 | TP |
| 1206 | harish p | grp des | 20000 | GR |
| 1207 |john | UI dev | 15000 | TP |
+------+--------------+-------------+-------------------+--------+