September 24, 2018

Sreekanth B

Dell EMC Pentaho Recently Asked Interview Questions Answers

How Do You Duplicate A Field In A Row In A Transformation?

Several solutions exist:

Use a “Select Values” step renaming a field while selecting also the original one. The result will be that the original field will be duplicated to another name.

It will look as follows:

This will duplicate fieldA to fieldB and fieldC.

Use a calculator step and use e.g. The NLV(A,B) operation as follows:

This will have the same effect as the first solution: 3 fields in the output which are copies of each other: fieldA, fieldB, and fieldC.

Use a JavaScript step to copy the field:

This will have the same effect as the previous solutions: 3 fields in the output which are copies of each other: fieldA, fieldB, and fieldC.

Why Can’t I Duplicate Fieldnames In A Single Row?

You can’t. PDI will complain in most of the cases if you have duplicate fieldnames. Before PDI v2.5.0 you were able to force duplicate fields, but also only the first value of the duplicate fields could ever be used.
Dell EMC Pentaho Recently Asked Interview Questions Answers
Dell EMC Pentaho Recently Asked Interview Questions Answers

I’ve Got A Transformation That Doesn’t Run Fast Enough, But It Is Hard To Tell In What Order To Optimize The Steps. What Should I Do?

Transformations stream data through their steps:

That means that the slowest step is going to determine the speed of a transformation.
So you optimize the slowest steps first. How can you tell which step is the slowest: look at the size of the input buffer in the log view.
In the latest 3.1.0-M1 nightly build you will also find a graphical overview of this: HTTP://WWW.IBRIDGE.BE/?P=92
(the “graph” button at the bottom of the log view will show the details).
A slow step will have consistently large input buffer sizes. A fast step will consistently have low input buffer sizes.

We Will Be Using Pdi Integrated In A Web Application Deployed On An Application Server. We’ve Created A Jndi Datasource In Our Application Server. Of Course Spoon Doesn’t Run In The Context Of The Application Server, So How Can We Use The Jndi Data Source In Pdi?

If you look in the PDI main directory you will see a sub-directory “simple-jndi”, which contains a file called “jdbc.properties”. You should change this file so that the JNDI information matches the one you use in your application server.

After that you set in the connection tab of Spoon the “Method of access” to JNDI, the “Connection type” to the type of database you’re using. And “Connection name” to the name of the JDNI datasource (as used in “jdbc.properties”).

Mention Major Features Of Pentaho?

Direct Analytics on MongoDB: It authorizes business analysts and IT to access, analyze, and visualize MongoDB data.

Science Pack: Pentaho’s Data Science Pack operationalizes analytical modeling and machine learning while allowing data scientists and developers to unburden the labor of data preparation to Pentaho Data Integration.

Full YARN Support for Hadoop: Pentaho’s YARN mixing enables organizations to exploit the full computing power of Hadoop while leveraging existing skillsets and technology investments.

Define Tuple?

Finite ordered list of elements is called as tuple.

What Kind Of Data, Cube Contain?

The Cube will contain the following data:

3 Fact fields: Sales, Costs and Discounts
Time Dimension: with the following hierarchy: Year, Quarter and Month

2 Customer Dimensions: one with location (Region, Country) and the other with Customer Group and Customer Name
Product Dimension: containing a Product Name

Differentiate Between Transformations And Jobs?

Transformations is moving and transforming rows from source to target.
Jobs are more about high level flow control.

How To Do A Database Join With Pdi?

If we want to join 2 tables from the same database, we can use a “Table Input” step and do the join in SQL itself.

If we want to join 2 tables that are not in the same database. We can use the the “Database Join”.
How To Sequentialize Transformations?

it is not possible as in PDI transformations all of the steps run in parallel. So we can’t sequentialize them.

How We Can Use Database Connections From Repository?

We can Create a new conversion or close and re-open the ones we have loaded in Spoon.

How Do You Insert Booleans Into A Mysql Database, Pdi Encodes A Boolean As ‘y’ Or ‘n’ And This Can’t Be Insert Into A Bit(1) Column In Mysql.?

BIT is not a standard SQL data type. It’s not even standard on MySQL as the meaning (core definition) changed from MySQL version 4 to 5.

Also a BIT uses 2 bytes on MySQL. That’s why in PDI we made the safe choice and went for a char(1) to store a boolean. There is a simple workaround available: change the data type with a Select Values step to “Integer” in the metadata tab. This converts it to 1 for “true” and 0 for “false”, just like MySQL expects.

By Default All Steps In A Transformation Run In Parallel, How Can We Make It So That 1 Row Gets Processed Completely Until The End Before The Next Row Is Processed?.

This is not possible as in PDI transformations all the steps run in parallel. So we can’t sequentialize them. This would require architectural changes to PDI and sequential processing also result in very slow processing.


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