What types of indexes have you used to optimize queries in your projects?

To optimize queries in projects, I used the following types of indexes:

• B-Tree indexes — standard indexes for fast equality and range searches, suitable for most cases.
• Hash indexes — effective for exact match searches but do not support range queries.
• Composite indexes — indexes on multiple columns, useful when queries filter on several fields simultaneously.
• Unique indexes — ensure the uniqueness of values and speed up searches.

For example, in PostgreSQL, creating a composite index:

CREATE INDEX idx_user_email_status ON users (email, status);

This will speed up queries filtering by email and status simultaneously.