Interview Questions.

Question 1. What Is The Role Of Jdbc Driver In A Sqoop Set Up?

Answer :

To hook up with exclusive relational databases sqoop wishes a connector. Almost every DB vendor makes this connecter to be had as a JDBC driver that is precise to that DB. So Sqoop wishes the JDBC driver of every of the database it wishes to inetract with.

Question 2. Is Jdbc Driver Enough To Connect Sqoop To The Databases?

Answer :

No. Sqoop desires each JDBC and connector to hook up with a database.

J2EE Interview Questions
Question three. When To Use Target-dir And When To Use Warehouse-dir While Importing Data?

Answer :

To specify a selected listing in HDFS use --goal-dir however to specify the figure listing of all of the sqoop jobs use warehouse-dir. In this situation below the figure directory sqoop will cerate a listing with the same name as th e desk.

Question 4. How Can You Import Only A Subset Of Rows Form A Table?

Answer :

By the usage of the WHERE clause inside the sqoop import announcement we can import only a subset of rows.

J2EE Tutorial
Question 5. How Can We Import A Subset Of Rows From A Table Without Using The Where Clause?

Answer :

We can run a filtering query at the database and save the result to a brief desk in database.Then use the sqoop import command without using the where clause

Data Warehousing Interview Questions
Question 6. What Is The Advantage Of Using Password-report Rather Than -p Option While Preventing The Display Of Password In The Sqoop Import Statement?

Answer :

The password-file alternative can be used interior a sqoop script at the same time as the -P option reads from general input , stopping automation.

Question 7. What Is The Default Extension Of The Files Produced From A Sqoop Import Using The --compress Parameter?

Answer :

.Gz

Data Warehousing Tutorial Hadoop Interview Questions
Question 8. What Is The Significance Of Using Compress-codec Parameter?

Answer :

To get the out record of a sqoop import in codecs other than .Gz like .Bz2 we use the compress -code parameter.

Question 9. What Is A Disadvantage Of Using Direct Parameter For Faster Data Load By Sqoop?

Answer :

The local utilities utilized by databases to guide faster laod do no longer work for binary statistics codecs like SequenceFile

Java Interview Questions
Question 10. How Can You Control The Number Of Mappers Used By The Sqoop Command?

Answer :

The Parameter num-mapers is used to govern the wide variety of mappers achieved by way of a sqoop command. We must start with choosing a small variety of map duties and then step by step scale up as deciding on high range of mappers initially might also slow down the performance at the database side.

Hadoop Tutorial
Question 11. How Can You Avoid Importing Tables One-by using-one When Importing A Large Number Of Tables From A Database?

Answer :

Using the command

sqoop import-all-tables

join
usrename
password
exclude-tables table1,table2 ..
This will import all of the tables except those stated within the exclude-tables clause.

Hadoop Administration Interview Questions
Question 12. When The Source Data Keeps Getting Updated Frequently, What Is The Approach To Keep It In Sync With The Data In Hdfs Imported By Sqoop?

Answer :

sqoop can have 2 approaches.

To use the incremental parameter with append option in which value of some columns are checked and handiest in case of modified values the row is imported as a new row.
To use the incremental parameter with lastmodified option in which a date column within the supply is checked for information that have been updated after the last import.
J2EE Interview Questions
Question 13. What Is The Usefulness Of The Options File In Sqoop?

Answer :

The alternatives record is utilized in sqoop to specify the command line values in a document and use it in the sqoop commands.

For example the --connect parameter's cost and --user name price scan be stored in a record and used over and over with exceptional sqoop instructions.

Java Tutorial
Question 14. Is It Possible To Add A Parameter While Running A Saved Job?

Answer :

Yes, we will add an issue to a saved activity at runtime by way of the use of the --exec alternative

sqoop job --exec jobname -- -- newparameter

Question 15. How Do You Fetch Data Which Is The Result Of Join Between Two Tables?How Can We Slice The Data To Be Imported To Multiple Parallel Tasks?

Answer :

Using the --split-by parameter we specify the column name based on which sqoop will divide the facts to be imported into more than one chunks to be run in parallel.

Scala Interview Questions
Question sixteen. How Can You Choose A Name For The Mapreduce Job Which Is Created On Submitting A Free-form Query Import?

Answer :

By the usage of the --mapreduce-task-call parameter. Below is a example of the command.

Sqoop import
--join jdbc:mysql://mysql.Instance.Com/sqoop
--username sqoop
--password sqoop
--query 'SELECT normcities.Identity,
nations.Country,
normcities.Metropolis
FROM normcities
JOIN international locations USING(country_id)
WHERE $CONDITIONS'
--cut up-via id
--goal-dir towns
--mapreduce-task-name normcities

Sqoop Tutorial
Question 17. Before Starting The Data Transfer Using Mapreduce Job, Sqoop Takes A Long Time To Retrieve The Minimum And Maximum Values Of Columns Mentioned In –cut up-by means of Parameter. How Can We Make It Efficient?

Answer :

We can use the --boundary –query parameter in which we specify the min and max value for the column primarily based on which the split can take place into more than one mapreduce obligations. This makes it faster as the question inside the –boundary-query parameter is executed first and the process is ready with the statistics on what number of mapreduce obligations to create before executing the principle question.

HBase Interview Questions
Question 18. What Is The Difference Between The Parameters?

Answer :

sqoop.Export.Information.According to.Declaration and sqoop.Export.Statements.Consistent with.Transaction

The parameter “sqoop.Export.Records.In step with.Announcement” specifies the wide variety of records so that it will be utilized in each insert statement.

But the parameter “sqoop.Export.Statements.According to.Transaction” specifies what number of insert statements can be processed parallel at some point of a transaction.

 

Data Warehousing Interview Questions
Question 19. How Will You Implement All-or-not anything Load Using Sqoop?

Answer :

Using the staging-table option we first load the records right into a staging table and then load it to the very last goal desk best if the staging load is a hit.

Scala Tutorial
Question 20. How Do You Clear The Data In A Staging Table Before Loading It By Sqoop?

Answer :

By specifying the –clean-staging-desk option we will clean the staging table before it's far loaded. This can be finished time and again until we get right statistics in staging.

Oozie Interview Questions
Question 21. How Will You Update The Rows That Are Already Exported?

Answer :

The parameter --replace-key can be used to update existing rows. In it a comma-separated list of columns is used which uniquely identifies a row. All of these columns is used in the WHERE clause of the generated UPDATE query. All other desk columns can be used in the SET a part of the query.

Question 22. How Can You Sync A Exported Table With Hdfs Data In Which Some Rows Are Deleted?

Answer :

Truncate the goal table and cargo it again.

HBase Tutorial
Question 23. How Can You Export Only A Subset Of Columns To A Relational Table Using Sqoop?

Answer :

By the use of the –column parameter in which we mention the specified column names as a comma separated list of values.

Hadoop Testing Interview Questions
Question 24. How Can We Load To A Column In A Relational Table Which Is Not Null But The Incoming Value From Hdfs Has A Null Value?

Answer :

By using the –enter-null-string parameter we can specify a default fee and in order to allow the row to be inserted into the goal table.

Hadoop Interview Questions
Question 25. How Can You Schedule A Sqoop Job Using Oozie?

Answer :

Oozie has in-built sqoop actions inner which we can mention the sqoop instructions to be carried out.

Question 26. Sqoop Imported A Table Successfully To Hbase But It Is Found That The Number Of Rows Is Fewer Than Expected. What Can Be The Cause?

Answer :

Some of the imported information would possibly have null values in all of the columns. As Hbase does now not permit all null values in a row, the ones rows get dropped.

Question 27. Give A Sqoop Command To Show All The Databases In A Mysql Server.?

Answer :

$ sqoop listing-databases --join jdbc:mysql://database.Example.Com/

Java Interview Questions
Question 28. What Do You Mean By Free Form Import In Sqoop?

Answer :

Sqoop can import records shape a relational database the use of any SQL question in place of handiest using desk and column call parameters.

Question 29. How Can You Force Sqoop To Execute A Free Form Sql Query Only Once And Import The Rows Serially?

Answer :

By using the –m 1 clause within the import command, sqoop cerates most effective one mapreduce mission which will import the rows sequentially.

Question 30. In A Sqoop Import Command You Have Mentioned To Run 8 Parallel Mapreduce Task But Sqoop Runs Only 4. What Can Be The Reason?

Answer :

The Mapreduce cluster is configured to run four parallel duties. So the sqoop command ought to have variety of parallel tasks less or identical to that of the MapReduce cluster.

Question 31. What Is The Importance Of --break up-with the aid of Clause In Running Parallel Import Tasks In Sqoop?

Answer :

The –split-via clause mentions the column call primarily based on whose price the information might be divided into organizations of information. These organization of records can be study in parallel by means of the mapreduce responsibilities.

Question 32. What Does This Sqoop Command Achieve?

Answer :

$ sqoop import --connnect <connect-str> --desk foo --target-dir /dest

It imports facts from a database to a HDFS document named foo located within the directory /dest

Question 33. What Happens When A Table Is Imported Into A Hdfs Directory Which Already Exists Using The –apend Parameter?

Answer :

Using the --append argument, Sqoop will import statistics to a brief directory and then rename the files into the ordinary goal directory in a way that does not conflict with present filenames in that listing.

Hadoop Administration Interview Questions
Question 34. How Can You Control The Mapping Between Sql Data Types And Java Types?

Answer :

By the use of the --map-column-java assets we are able to configure the mapping between.

Below is an example : $ sqoop import ... --map-column-java id = String, price = Integer

Question 35. How To Import Only The Updated Rows Form A Table Into Hdfs Using Sqoop Assuming The Source Has Last Update Timestamp Details For Each Row?

Answer :

By using the lastmodified mode. Rows wherein the test column holds a timestamp more current than the timestamp special with --ultimate-fee are imported.

Question 36. What Are The Two File Formats Supported By Sqoop For Import?

Answer :

Delimited text and Sequence Files.

Scala Interview Questions
Question 37. Give A Sqoop Command To Import The Columns Employee_id,first_name,last_name From The Mysql Table Employee?

Answer :

$ sqoop import --join jdbc:mysql://host/dbname --desk EMPLOYEES
    --columns "employee_id,first_name,last_name" 

Question 38. Give A Sqoop Command To Run Only 8 Mapreduce Tasks In Parallel?

Answer :

$ sqoop import --connect jdbc:mysql://host/dbname --table table_name
    -m eight

Question 39. What Does The Following Query Do?
$ Sqoop Import --join Jdbc:mysql://host/dbname --desk Employees     --where "start_date > '2017-03-31'

Answer :

It imports the employees who've joined after 31-Mar-2017.

Question forty. Give A Sqoop Command To Import All The Records From Employee Table Divided Into Groups Of Records By The Values In The Column Department_id.?

Answer :

$ sqoop import --join jdbc:mysql://db.Foo.Com/corp --desk EMPLOYEES
   --split-by using dept_id

HBase Interview Questions
Question 41. What Does The Following Query Do?
$ Sqoop Import --join Jdbc:mysql://db.Foo.Com/somedb --table Sometable
--in which "id > one thousand" --target-dir /incremental_dataset --append

Answer :

It performs an incremental import of recent statistics, after having already imported the primary a hundred,0rows of a table

Question forty two. Give A Sqoop Command To Import Data From All Tables In The Mysql Db Db1.?

Answer :

sqoop import-all-tables --join jdbc:mysql://host/DB1

Oozie Interview Questions
Question forty three. Give A Command To Execute A Stored Procedure Named Proc1 Which Exports Data To From Mysql Db Named Db1 Into A Hdfs Directory Named Dir1.?

Answer :

$ sqoop export --join jdbc:mysql://host/DB1 --call proc1
      --export-dir /Dir1

Question 44. What Is A Sqoop Metastore?

Answer :

It is a device the usage of which Sqoop hosts a shared metadata repository. Multiple customers and/or far off users can outline and execute stored jobs (created with sqoop task) described in this metastore.

Clients ought to be configured to connect with the metastore in sqoop-website.Xml or with the --meta-connect argument.

Question forty five. What Is The Purpose Of Sqoop-merge?

Answer :

The merge tool combines  datasets where entries in a single dataset have to overwrite entries of an older dataset preserving simplest the most recent version of the data among each the facts units.

Question 46. How Can You See The List Of Stored Jobs In Sqoop Metastore?

Answer :

sqoop process –list

Question forty seven. Give The Sqoop Command To See The Content Of The Job Named Myjob?

Answer :

Sqoop process –display myjob

Question forty eight. Which Database The Sqoop Metastore Runs On?

Answer :

Running sqoop-metastore launches a shared HSQLDB database example on the current machine.

Question forty nine. Where Can The Metastore Database Be Hosted?

Answer :

The metastore database may be hosted everywhere within or out of doors of the Hadoop cluster..