OLAP vs OLTP: Analytical vs Transactional Databases

Explain the difference between OLAP and OLTP.

OLTP (Online Transaction Processing)

Designed for day-to-day business transactions (orders, logins, updates).

Characteristics:

• High-frequency, short read/write operations.
• Strict ACID transaction guarantees.
• Each operation touches few rows (a single order).
• Normalized schema (minimize data duplication).

Examples: PostgreSQL, MySQL, Oracle

OLAP (Online Analytical Processing)

Designed for complex analytical queries over large datasets (monthly sales reports, user behavior analysis).

Characteristics:

• Low-frequency, long-running queries.
• Each query may scan millions of rows.
• Primarily reads; writes are usually batch loads.
• Denormalized schema (star schema) to reduce JOINs.
• Columnar storage improves aggregation performance.

Examples: Snowflake, BigQuery, Redshift, ClickHouse

Why Separate Them

Mixing them causes analytical queries to degrade the transactional system. ETL/ELT pipelines copy OLTP data to OLAP systems.