Which column is the best candidate for an index from a selectivity perspective?

Problem Statement

Explanation

High-selectivity columns filter out many rows per lookup. Unique keys are the most selective and typically index well. Low-cardinality columns like boolean flags rarely help alone, though they can help as the leading column in a composite index for special cases.

Code Solution

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CREATE UNIQUE INDEX idx_users_email ON users(email);

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Indexes & Query Performance Essentials

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Which column is the best candidate for an index from a selectivity perspective?

Problem Statement

Explanation

Code Solution

Practice Sets

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Master Interviews Anywhere, Anytime

Which column is the best candidate for an index from a selectivity perspective?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews
Anywhere, Anytime