sqoop scenario based questions - Wikitechy

What is the difference between sqoop and pig ?

Editor — Thu, 22 Jul 2021 06:59:29 +0000

Pig:

Pig is a platform for managing large data.
It uses high level programming to analyse the data.
The programming is done using the language pig latin.
It is simple and highly specific.
The pig Metastore stores all info about the tables. And we can execute spark sql queries because spark can interact with pig Metastore

Sqoop:

Sqoop is a simple tool used for transferring large amount of data.
It is used for transferring data from hadoop to relational database.
sqoop can import data from Oracle,MYSQL,SQl.
Sqoop metastore is a tool for using hosts in a shared metadata repository. Multiple users and remote users execute saved jobs in metastore.

What is staging table in sqoop ?

Editor — Thu, 22 Jul 2021 06:53:48 +0000

Staging table in sqoop:

Staging table is used to stage the exported data.
Sqoop breaks down method into multiple transactions. A failing job may create partial knowledge.
This could result in job failing because it could cause duplication of data or even collision while insertion.
Staging tables are simple database tables that contain business details.
Staging table acts as an auxiliary table that’s used to transferred data.
Sqoop breaks down export method into multiple transactions, it’s possible that a failing export job may lead to partial data being committed to the database

What is update command in sqoop ?

Editor — Thu, 22 Jul 2021 06:52:07 +0000

Update command in sqoop:

There are two approaches to update in sqoop.
- The records inserted are to be added to the target table.
- The sqoop provides an update mode by providing “update-key ” command.
This command is used to generate the SQl update statement.
If the value in column 1 matches the data is updated else the data is inserted into the table.
This technique is also refered to as upsert where the default action is update but insertion takes place when matching data is not available.

 
$ sqoop export (Generic Arguments)
  --table target-relational-table 
  --update-key column1
  --export-dir /user/my-hdfs-file
  ...
Generates => UPDATE target-relational-table SET
                    column2=1000,column3=2000
		          WHERE column1=100;

What is the use of sqoop ?

Editor — Thu, 22 Jul 2021 06:49:42 +0000

Sqoop uses:

Sqoop is a simple tool that is used for moving data.
It is generally used move data from non hadoop data stores.
These non hadoop data stores are the relational databases and data warehouses .
Sqoop allows the users to specify the target (i.e) the place where the data is to be moved inside of hadoop from relational databases like Oracle,Teredata.
Data ingestion is important in any big data project because the volume of data is generally in petabytes or exabytes.
Hadoop Sqoop and Hadoop Flume are the two tools in Hadoop which is used to gather data from different sources and load them into HDFS.

What is sqoop metastore ?

Editor — Thu, 22 Jul 2021 06:47:16 +0000

Sqoop Metastore:

Sqoop metastore is an internally implemented database that can hold the definition of a given job.
It includes details like which database,which table,which approach,what query to extract from,what target to write to and so on.
Consider an array of SQL databases that have the same structure, but are partitioned by for performance reasons.
Thus we have the same sqoop job running against multiple database instances at the same time, all unified at a single table in Hadoop.
In order to get parallelization, we generate a job that manages the Sqoop sub-workflows. This results in 500 distinct sqoop jobs.
Metastore is used to handle these complexities.

What is sqoop ?

Editor — Thu, 22 Jul 2021 06:22:24 +0000

Sqoop:

Apache Sqoop is efficiently transferring data between Relational databases and Apache Hadoop.
It is used to import data from relational databases such as MySQL, Oracle to Hadoop HDFS, and export from Hadoop file system to relational databases.
It improves the efficiency of data analysis by combining structured data and unstructured data.
Sqoop stands for SQL for Hadoop.SQL + HADOOP =SQOOP

What is the process to perform an incremental data load in sqoop ?

Editor — Mon, 12 Jul 2021 19:32:34 +0000

Process to perform an incremental data load in sqoop:

- Sqoop provides an incremental import mode which can be used to retrieve only rows newer than some previously-imported set of rows.

Sqoop supports two types of incremental imports: append and lastmodified. You can use the --incremental argument to specify the type of incremental import to perform.
You must specify append mode when importing a table where new rows are frequently being inserted with increasing row id values. You can specify the column containing the row’s id with --check-column. Sqoop imports rows where the verify column have a value greater than the single specified with --last-value.
An alternating table update strategy supports by Sqoop is known lastmodified mode. You must use this while rows of the source table might be updated, and then each such update will set the value of a last-modified column to the present timestamp. Rows where have the check column holds a timestamp more and more new than the timestamp specified with --last-value are imported.