For a composite index on (country_code, email), which predicate can fully seek the index?

Problem Statement

Explanation

Composite indexes are left-prefix. To fully seek, you must filter on the leading column(s). Filtering only on the second column often needs a scan. Plan index column order by your most common predicates and how they combine.

Code Solution

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CREATE INDEX idx_users_cc_email ON users(country_code, email);

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This question appears in the following practice sets:

Indexes & Query Performance Essentials

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For a composite index on (country_code, email), which predicate can fully seek the index?

Problem Statement

Explanation

Code Solution

Practice Sets

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

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Master Interviews Anywhere, Anytime

For a composite index on (country_code, email), which predicate can fully seek the index?

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