What types of indexes were used? Were there any negative costs associated with the indexes?

In projects, I used several types of indexes:

• B-tree indexes for fast searches on fields with equalities and ranges.
• Hash indexes to speed up exact searches (e.g., on unique keys).
• Full-text indexes for searching text fields.
• Composite indexes to optimize queries with multiple conditions.

Negative impacts of indexes include:

• Slowing down write operations (INSERT, UPDATE, DELETE) because indexes need to be updated.
• Increasing the storage space used in the database.
• The possibility of inefficient index usage due to poor design, which can lead to performance degradation.

Therefore, it is important to carefully select which fields to index and regularly analyze query execution plans.