Databases · Middle · Question 3 of 75

There's an index on `created_at`. Why might `WHERE date(created_at) = '2026-11-01'` ignore it?

1The date() function is not supported in PostgreSQL
✓Correct answer: A function on the column changes the value, so the index on the raw column can't be searched; use a range or an expression index
3Indexes don't work with dates

Explanation

Rewrite as created_at >= '2026-11-01' AND created_at < '2026-11-02', or create an index on the expression itself.

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