How did you realize that indexes were missing? Why did you use a B-tree index?

The disadvantage of indexes usually manifests as a slowdown in query execution, especially when selecting with conditions on fields that are not indexed. This can be observed by the long response time, analysis of the execution plan (EXPLAIN), where a full table scan is visible.

A B-tree index is used because it is efficient for quick searches within ranges, exact matches, and sorting. It maintains a balanced structure, which provides logarithmic access time to data.

Example: if we have a users table with a "username" field, and we often run queries like

SELECT * FROM users WHERE username = 'ivan';

then creating a B-tree index on the username field will speed up the search, as the index allows quick access to the needed record without scanning the entire table.

CREATE INDEX idx_username ON users(username);

Thus, a B-tree index is a universal and effective way to accelerate search and sorting on key fields.