What is Sqoop and What Does Sqoop Stand For?
Sqoop stands for SQL-to-Hadoop. Apache Sqoop is a tool in the Hadoop ecosystem used for transferring bulk data between relational databases and the Hadoop Distributed File System (HDFS). It can import data from RDBMS (like MySQL, Oracle) into HDFS and export data back from HDFS to RDBMS.
What is Sqoop Used For?
Sqoop is primarily used for importing and exporting large volumes of data between relational databases and Hadoop. It simplifies the data transfer process, making it efficient and fault-tolerant through the use of MapReduce.
What is the Default Database of Sqoop?
Sqoop does not have a "default database" but most documentation and examples use MySQL for demonstration purposes.
How to Check Sqoop Version?
Use the following command in the terminal:
sqoop version
How to Set Number of Mappers in Apache Sqoop?
You can control the number of mappers using the --num-mappers option. Example:
--num-mappers 10
What is Sqoop Direct Mode?
Direct mode in Sqoop allows data to be imported/exported using native utilities for better performance. It currently supports MySQL and PostgreSQL databases.
How to Delete a Sqoop Job?
You can delete a saved Sqoop job using:
sqoop job --delete <job-id>
What is Sqoop Eval Tool?
Sqoop Eval is used to execute simple SQL statements (DDL or DML) on a database using Sqoop. Example:
sqoop eval --connect jdbc:mysql://localhost/db --username user --password pass --query "SELECT * FROM table"
Why is Sqoop Used in Hadoop?
Sqoop helps import/export data between Hadoop and RDBMS. It automates the data transfer using MapReduce, ensuring fault tolerance and high performance.
What is Boundary Query in Sqoop?
Boundary query is used to explicitly define the min and max values for a column during parallel imports using the --split-by option.
How to Import Multiple Tables in Sqoop?
Use the import-all-tables command:
sqoop import-all-tables --connect <connection-string> --username <user> --password <pass>
Conditions:
- Each table must have a primary key.
- All columns are imported.
- WHERE clause and custom split-by not allowed.
How to Change Sqoop Date Format?
To change date format, use the --map-column-java option or configure format handling through a custom transformation logic.
What is the Difference Between Sqoop and Flume?
| Sqoop | Flume |
|---|---|
| Used for structured data from RDBMS. | Used for streaming data like logs. |
| Connector-based architecture. | Agent-based architecture. |
| No event-driven support. | Event-driven. |
| Optimized for batch data transfer. | Optimized for log aggregation. |
What Happens if Sqoop Job Fails During Transfer?
If a job fails, partial data may be stored. Use --staging-table to safely stage the data before the final commit.
What is the Use of Split By in Sqoop?
The --split-by option allows parallel data import based on the specified column.
How to Use Split By in Sqoop?
--split-by student.id
What is Accumulo in Sqoop?
Apache Accumulo is a key-value store built on HDFS. Sqoop can import data from or export to Accumulo using connectors.
How to Grant Access on Password File in Sqoop?
echo -n "password" > /etc/sqoop/conf/passwords/mysql-password.txt
chmod 400 /etc/sqoop/conf/passwords/mysql-password.txt
sqoop import --connect jdbc:netezza://localhost/MYDB \
--username testuser --table ORDERS \
--password-file /etc/sqoop/conf/passwords/mysql-password.txt
How Incremental Import Works in Sqoop?
Sqoop supports two types of incremental imports: append and lastmodified. After a job, the last imported value is shown, which should be used in the next run to fetch only updated data.
How Much Memory Does Sqoop Client Need?
Sqoop requires approximately 1GB of memory for job initialization.
What is Free Form Import in Sqoop?
Free-form import allows custom SQL queries using --query. Example:
sqoop import --query "SELECT id, name FROM users WHERE $CONDITIONS" --split-by id
How to Pass Schema Name in Sqoop?
sqoop import ... --table custom_table -- --schema custom_schema
How to List Databases in Sqoop?
sqoop list-databases --connect <jdbc-url> --username user --password pass
Why Use $CONDITIONS in Sqoop?
The $CONDITIONS placeholder is used in free-form queries to support parallel execution. Sqoop replaces it with appropriate WHERE conditions for each mapper.