10+ ETL Talend Developer Interview Questions and Answers

SCD type 2 is a method of tracking historical changes in data, while incremental load is the process of updating only new or changed data.

• SCD type 2 involves creating a new record for each change in data, with a start and end date for each version.

• Incremental load involves comparing new data to existing data and only updating or inserting new records.

• Both are commonly used in data warehousing and ETL processes.

• Example: tracking changes in customer addresses over time using SC...read more

Parallel processing in Talend allows for executing multiple tasks simultaneously, improving performance.

• Use tParallelize component to run subjobs in parallel

• Enable parallel execution in job settings

• Utilize tFlowToIterate to process data in parallel

• Implement parallel processing for large data sets to optimize performance

Filter source data by department id and store in unique files

• Use Talend components like tFilterRow to filter data based on department id

• Create a unique file for each department using tFileOutputDelimited component

• Loop through all department ids to process data for each department

Tools and technologies used for solving ETL problems

• Talend Open Studio for Data Integration

• Apache NiFi

• AWS Glue

• Microsoft SQL Server Integration Services (SSIS)

• Oracle Data Integrator (ODI)

• IBM InfoSphere DataStage

Optimizing SQL queries can improve query performance by using indexes, avoiding unnecessary joins, and optimizing the query structure.

• Use indexes on columns frequently used in WHERE clauses

• Avoid using SELECT * and only retrieve necessary columns

• Optimize joins by using INNER JOIN instead of OUTER JOIN when possible

• Use WHERE clause to filter data early in the query

• Avoid using functions in WHERE clauses as they can prevent index usage

Global variables are accessible throughout the job, while context parameters are specific to a job or component.

• Global variables can be used across multiple jobs, while context parameters are limited to a single job or component.

• Global variables are defined at the project level, while context parameters are defined at the job level.

• Global variables can be modified during runtime, while context parameters are read-only.

• Example: A global variable could be used to store a databa...read more

I am currently working on Talend version 7.3.1.

• Working on Talend version 7.3.1

• Familiar with the features and updates in this version

• Experience in developing ETL processes using this version

I have worked with various Talend components including tMap, tFilterRow, tAggregateRow, tSortRow, tFileInputDelimited, tFileOutputDelimited, tJavaFlex, tJavaRow, tNormalize, tDenormalize, tPivotToColumnsDelimited, tUnpivot, tReplace, tExtractRegexFields, tExtractXMLField, tExtractJSONField, tConvertType, tJoin, tReplicate, tSample, tRandom, tSystem, tSleep, tWarn, tDie, tSendMail, tFTP, tSSH, tS3Input, tS3Output, tRedshiftInput, tRedshiftOutput, tSalesforceInput, tSalesforceO...read more

Schemas in Talend are used to define the structure of data being processed.

• Schemas define the columns and data types of input and output data in Talend jobs.

• They can be imported from databases, defined manually, or generated automatically.

• Schemas help ensure data quality and consistency in ETL processes.