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SQLtest.online
Task 13:
A pipeline loads customer data from a CRM, billing system, and product database, but the same customer has different IDs in each system. How would you design the data model and matching logic so analytics teams can use one reliable customer view?

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Who is a Data Engineer?

A Data Engineer designs and maintains systems that collect, transform, and deliver data for analytics and business decisions.

What does a Data Engineer do?

  • Builds reliable ETL/ELT pipelines from multiple data sources.
  • Prepares clean and structured datasets for analysts and data scientists.
  • Designs data warehouse schemas (fact and dimension tables).
  • Monitors data quality, freshness, and pipeline failures.
  • Optimizes query performance and data processing costs.

What should a Data Engineer know?

  • Strong SQL: joins, aggregations, window functions, and query tuning.
  • Data modeling: normalization, denormalization, star and snowflake schemas.
  • Pipeline orchestration and scheduling principles.
  • Batch and streaming concepts, incremental loading, and idempotency.
  • Cloud storage, data warehouses, and observability basics.

This page helps you practice interview-style Data Engineering questions on SQLTest.online.

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Head First SQL: A Learner's Guide to Querying and Managing Data by Kimberly Fessel
Head First SQL: A Learner's Guide to Querying and Managing Data by Kimberly Fessel
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