Did you rewrite the index or the query — what exactly changed in the query?

If the index or query is rewritten, the following changes occur:

• When rewriting an index: the data structure used to speed up searches is changed. For example, the index type (B-tree, Hash), the set of columns, the order of columns, or indexes are added/removed. This affects the execution plan of the query, allowing the database to find the required records more efficiently.

• When rewriting a query: the SQL code itself changes: the logic of selection, filtering conditions, table joins, sorting order, etc., may change. This affects what data is retrieved and how.

Ultimately, rewriting an index optimizes data access methods, while rewriting a query changes the logic and structure of data retrieval. These changes are often interconnected: a new index allows rewriting the query more efficiently, and a modified query may require a different index for optimal performance.