In what situations and why might ORM be ineffective or undesirable?

The use of ORM (Object-Relational Mapping) can be inefficient or undesirable in the following situations:

• High performance requirements: ORM adds an extra layer of abstraction, which can lead to reduced performance for complex queries or large volumes of data.
• Complex or specific SQL queries: If you need to use complex JOINs, subqueries, stored procedures, or database-specific features, ORM may limit flexibility.
• Small projects or simple tasks: For simple database operations, using ORM can be excessive and complicate the code.
• Fine-tuning queries: When optimizing each query is important, manually writing SQL is often preferable.
• Migration and schema issues: ORM can sometimes be difficult to adapt to changes in the database structure, especially in large projects.

Example: if a project requires executing a complex analytical query with multiple subqueries and aggregates, it is better to write SQL directly than to try to implement it through ORM.