Choosing Composite Index Column Order

Problem

A frequent query is `WHERE country = ? AND city = ? AND signup_d >= ?`. Should you create the index as `(country, city, signup_d)` or `(signup_d, country, city)`? Explain.

Input

Conceptual.

Output

Explanation

Constraints

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Sample input

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Sample output

Equality predicates first, then range. `(country, city, signup_d)` because country and city are equalities and signup_d is a range.

Explanation

Indexes only use the leftmost equality columns; once a range is hit, deeper columns can't be index-seeked.

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