Sqoop for database imports in Hadoop - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Sqoop used for in Hadoop?

Sqoop is a tool that helps transfer data between Hadoop and relational databases. It is mainly used to import data from databases into Hadoop's HDFS and export data back.

beginner

Which command imports a full table from a database into HDFS using Sqoop?

The command is <code>sqoop import --connect &lt;jdbc-connection-string&gt; --table &lt;table-name&gt; --username &lt;user&gt; --password &lt;password&gt; --target-dir &lt;hdfs-directory&gt;</code>. This imports the entire table into the specified HDFS directory.

intermediate

What does the --split-by option do in Sqoop import?

The <code>--split-by</code> option tells Sqoop which column to use to split the data for parallel import. This helps speed up the import by dividing the work across multiple mappers.

intermediate

How can you import only specific columns from a database table using Sqoop?

Use the --columns option with a comma-separated list of column names. For example, --columns "id,name,age" imports only those columns.

intermediate

What is the role of the --where clause in Sqoop import?

The <code>--where</code> clause lets you filter rows during import by specifying a SQL condition. For example, <code>--where "age &gt; 30"</code> imports only rows where age is greater than 30.

What does Sqoop primarily do?

A Processes big data inside Hadoop

B Transfers data between Hadoop and relational databases

C Visualizes data in Hadoop

D Manages Hadoop cluster nodes

Sqoop is designed to transfer data between Hadoop and relational databases.

Which option specifies the database table to import in Sqoop?

A --table

B --connect

C --target-dir

D --split-by

The --table option tells Sqoop which database table to import.

How does Sqoop speed up data import?

A By using multiple mappers with --split-by

B By compressing data

C By importing only metadata

D By exporting data instead

Sqoop uses multiple mappers and the --split-by option to parallelize data import.

Which option filters rows during import?

A --columns

B --username

C --where

D --target-dir

The --where option applies a SQL condition to filter rows during import.

To import only specific columns, which option do you use?

A --table

B --split-by

C --connect

D --columns

The --columns option lets you specify which columns to import.

Explain how Sqoop imports data from a relational database into Hadoop.

Think about the steps and options needed to move data from a database to Hadoop.

Describe how you can control which data Sqoop imports from a database table.

Consider options that limit or organize the data imported.