What indexes did you use, on which fields did you choose and why?.

The choice of indexes depends on the query structure and the fields used in WHERE, JOIN, ORDER BY.

• B-tree indexes — universal, suitable for equality and range queries. Used on fields with high selectivity.
• Hash indexes — effective for exact match searches, but do not support ranges.
• Composite indexes — index on multiple fields, useful when queries filter on several columns simultaneously.
• Indexes on foreign keys — speed up JOINs.

Example: if users are often searched by email, an index on email is created, as searching by email is a common operation with high selectivity.

In Go, when working with databases, indexes are created on the DBMS side, and it is important to write queries that utilize these indexes (for example, filters on indexed fields).