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Can you explain the difference between OLTP and OLAP?

SQLmedium0.4 min read

**OLTP**: Optimized for many small transactions (inserts, updates, deletes). Row-oriented, normalized, high concurrency. Examples: MySQL, PostgreSQL. **OLAP**: Optimized for complex analytical queries and aggregations on large datasets. Column-oriented, denormalized...

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Frequency
Low
Asked at 4 companies
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
AccentureCognizantEPAMYash Technologies
Interview Pro Tip

Red Flag: Saying OLAP is 'faster' without specifying 'for analytical workloads.' Pro-Move: Mention that modern stacks use CDC to move OLTP data into OLAP; avoid running analytics on OLTP.

Key Concepts Tested
bigquerysnowflakesql

Why This Question Matters

This medium-level SQL question appears frequently in data engineering interviews at companies like Accenture, Cognizant, EPAM, and 1 others. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (bigquery, snowflake, sql) will help you answer variations of this question confidently.

How to Approach This

Break this problem into components. Identify the core trade-offs involved, then walk the interviewer through your reasoning step by step. Demonstrate awareness of edge cases and production considerations - this is what separates good answers from great ones.

Expert Answer
86 words

OLTP: Optimized for many small transactions (inserts, updates, deletes). Row-oriented, normalized, high concurrency. Examples: MySQL, PostgreSQL. OLAP: Optimized for complex analytical queries and aggregations on large datasets. Column-oriented, denormalized (star/snowflake). Examples: Snowflake, BigQuery, Redshift. Why the split: Different access patterns; mixing them degrades both. OLTP needs low latency and ACID; OLAP needs scan throughput. Scalability: OLTP scales via replication and sharding; OLAP via MPP and columnar storage. Cost: OLTP is usually more expensive per GB due to indexing and replication; OLAP is optimized for bulk scans.

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