Talend Data Integration Interview Questions and Answers

Talend Open Studio

Talend Open Studio for Data Integration is an open source data integration product developed by Talend and designed to combine, convert and update data in various locations across a business.

Launched in October 2006

ETL stands for Extract, Transform and Load which is a process that involves gaining data from exterior source, converting it to get fit into operational requirement, then load it into the end target database.

ELT stands for Extract, Load and Transform which is the process in which data is get, then loaded into the staging table in the database and then data is converted according to the need.

It is a component for mailing correct address belongs to the respective customer data to make sure a single customer view and good delivery for their respective customer mailing.

We can change the background of job designer by clicking on the preferences of the window menus, after the talend, appearance,designer then click on color menu.

Component is simply a functional piece which is used for a single operation. It is a bundle of file kept within a folder named followed by component name.

Insert or Update: First tries to insert a record, but if a record with a matching primary key already exists, instead updates that record.

Update or Insert: First tries to update a record with a matching primary key, but if none already exists, instead inserts the record.

From a results point of view, there are no differences between the two, nor are there significant performance differences. In general, choose the action that matches what you expect to be more common: Insert or Update if you think there are more inserts than updates, Update or Insert if you think there are more updates than inserts.

In Built-In we can manually edit the data as data is kept locally in the job whereas in repository all the data is stored there only. We can extract only Read-only-information into the job from repository.

It simply depends on the way we use it. We should use Built-in for the data which we use rarely and use the Repository for the data which we use repeatedly.

OnSubjobOK and OnComponentOK are trigger links, which can link to another subjob.

The main difference between OnSubjobOK and OnComponentOK lies in the execution order of the linked subjob. With OnSubjobOK, the linked subjob starts only when the previous subjob completely finishes. With OnComponentOK, the linked subjob starts when the previous component finishes.

tMap is the latest component which simply converts and routes data from one or many sources to one or many destinations.

• data transformation on any type of fields
• data multiplexing and demultiplexing
• fields concatenation and interchange
• data rejecting
• field filtering using constraints

Inner, outer, unique, first, and all joins

tDenormalizeSortedRow combines in a group all input sorted rows. Distinct values of the denormalized sorted row are joined with item separators. tDenormalizeSortedRow helps synthesizing sorted input flow to save memory.

tJoin joins two tables by doing an exact match on several columns. It compares columns from the main flow with reference columns from the lookup flows and outputs the main flow data and/or the rejected data.

What is the use of Numeric Routine?

It allows us to revisit whole or decimal numbers in order to use them as setting in one or more job mechanism.

This Component is used to correct mailing addresses associated with customer data to ensure a single customer view and better delivery for their customer mailings.

With using this we can add various input and output flow as needed into the visual map editor to execute.

It shows many information belongs to the open job on the design workspace.

It allows us to take out many operations and test on alphanumeric expressions relay on Java methods.

tSortRow, tExternalSortRow

tAggregateRow – accepts input data even if it is not sorted

tAggregateSortedRow – accepts only sorted input, if data is not sorted before this component, job goes into infinite loop.

Hence tSortRow component must be used before taggregatesortedrow if input data to this component is not sorted already.

tAggregateRow – Number of input rows to this component, need not be specified.

tAggregateSortedRow– Number of input rows to this component, must be specified.

if not sure about no of rows that are going to flow from this component to next component then you can specify -1 there.

tMap is frequently used component for joins and lookup purpose, it is also use for verity of operations and transformations, whereas tJoin is used for join and lookups only.

tJava: this component can be use as trigger component, At start of the job at end of the job.

tJavaRow: this component required main flow so it can be used at end of the Sub Job but not at the start of subjob.

tJavaFlex: this component holds capabilities of tJava & tJavaRows you can use this component for row generation, or at start of job, or at then end of sub job. or individual subjob. It gives you ability to auto propagate data.

If you want to add/load third party libraries in Talend Project, then you can choose any of the solution below.

• Window -> Preferences -> Java -> User Libraries This will include jar files for all the project jobs.
• Use the tLibraryLoad component to load a lib file in a job.
• Use Routines “Edit Routine Libraries” option
  • Right click on Routine
  • Select Option “Edit Routine Libraries“
  • On popup window click on “New” Button.
  • Select “Browse a Library file” option.
  • Browse and select required Library.
  • Click on “if the library file is required” click “Ok”.
• Another ways is use “Module” Tab to download and installed Library.