Why is Redis used for caching, and Postgres for transactions?

Redis is used for caching because:

• It is an in-memory store with very high access speed.
• Supports data structures suitable for caching (strings, lists, sets).
• Provides expiration mechanisms (TTL) for automatic removal of outdated data.

Postgres is used for transactions because:

• It is a relational database management system with support for ACID transactions, ensuring data integrity.
• Supports complex queries and relationships between tables.
• Provides reliable disk storage and recovery after failures.

Thus, Redis is optimal for fast temporary data storage, while Postgres is suitable for reliable long-term storage with consistency guarantees.