The query takes a very long time to execute. What can be done to make it faster?

To speed up the execution of a long query, the following steps can be taken:

• Query execution plan analysis: see which operations take the most time.
• Indexing: add or optimize indexes on columns involved in filtering and joins.
• Query optimization: rewrite the query, remove redundant subqueries, use more efficient constructs.
• Query partitioning: if possible, split a complex query into several simpler ones.
• Result caching: if data does not change often, use caching.
• Parallelization: utilize the database management system's capabilities for parallel execution.

Example: if a query runs slowly due to the absence of an index on the user_id column in the orders table, adding an index can significantly speed up the selection:

CREATE INDEX idx_orders_user_id ON orders(user_id);

Each case is individual, so it is important to understand the bottlenecks first.