What is the main problem of this implementation - Index may not be mandatory - Incorrect index type used to achieve the desired goals. - There is a composite index - The table is not normalized - No use of transactions

The main issue with this implementation may be that the wrong type of index was chosen to achieve the goals. For example, if the index does not cover the necessary queries or does not consider the data characteristics, its efficiency decreases.

Other possible problems:

• The index may be optional, meaning queries do not always use it, which reduces its benefit.
• The presence of a composite index that does not match the order of conditions in queries, causing the index not to be used.
• The table is not normalized, leading to data redundancy and complicating indexing.
• The lack of transaction usage may lead to data integrity issues during parallel operations.

To accurately identify the problem, it is necessary to analyze the table structure, index types, and the nature of the queries.