What are the main difficulties encountered when forming index structures in a database?

The main difficulties in forming index structures in a database are related to balancing performance with the costs of storing and updating indexes:

• Choosing the appropriate type of index for specific queries (e.g., B-trees, hash indexes).
• Ensuring efficiency during insertions, updates, and deletions, as indexes require additional time to maintain relevance.
• Managing the size of indexes so they do not occupy too much space or slow down operations.
• Avoiding redundant or duplicate indexes that could degrade performance.
• Ensuring proper index selectivity so that it genuinely speeds up queries.

For example, creating too many indexes on a table can significantly slow down write operations due to the need to update all indexes.