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Data Modeling and Schema Design Questions

Focuses on designing efficient, maintainable data schemas for transactional and analytical systems. Candidates should demonstrate understanding of normalization principles and normal forms, when and why to denormalize for performance, and schema design patterns for different use cases. Expect dimensional modeling topics including fact and dimension tables, star and snowflake schemas, grain definition, slowly changing dimensions, and strategies for handling historical data. The topic also includes trade offs between online transaction processing and online analytical processing designs, query performance considerations, indexing and partitioning strategies, and the ability to evaluate and improve existing schemas to meet business requirements and scale.

MediumTechnical
29 practiced
Create a migration plan (high level) to convert a busy orders table from storing full addresses inline to referencing an addresses table (normalization), ensuring no downtime and minimal risk. Include steps for data migration, application compatibility, and rollback.
HardSystem Design
32 practiced
A global company needs to shard its customer table across regions. Propose a logical sharding key and schema-level strategies for joins with orders that reference customers across shards. Discuss handling cross-shard transactions and referential integrity.
EasyTechnical
41 practiced
Describe Slowly Changing Dimension (SCD) types 0, 1, 2, and 3. For each type give a concrete use case where it is appropriate to use.
MediumTechnical
41 practiced
You have a fact table that is heavily used for aggregations by customer and product. Query profiling shows many slow GROUP BY queries. Propose schema-level and physical-design changes to speed up aggregation queries without significantly increasing write latency.
EasyTechnical
38 practiced
Describe how partitioning a large fact table by date can improve query performance. What partitioning scheme would you use for a table containing 10 years of daily e-commerce transaction lines and why?

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