Database Error

What This Error Means

This error occurs when a SQL query attempts to use an index with the IN operator on a derived table that also uses a window function. The IN operator can't be used in this way because it doesn't allow for the efficient use of an index.

Why It Happens

This error typically happens when a developer is writing a complex SQL query that uses a derived table (a subquery in the FROM clause) and also applies a window function to the data. The IN operator is then used to filter the results, but the database can't optimize the query effectively because of the way the IN operator interacts with the index.

How to Fix It

1. 1To fix this error, the developer should restructure the query to avoid using the IN operator with a derived table and window function. One possible solution is to use a JOIN instead of a derived table, or to apply the window function to the individual tables before joining them.

Example Code Solution

SELECT * FROM (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY created_at) AS row_num
  FROM orders
) AS subquery
WHERE id IN (SELECT id FROM customers WHERE country = 'USA')

SELECT o.*
FROM orders o
JOIN customers c ON o.id = c.id
WHERE c.country = 'USA'