What is selectivity/cardinality and why does it matter for indexing?

What is selectivity/cardinality and why does it matter for indexing?

题目类型: 技术面试题

这是一道技术面试题，常见于澳洲IT公司面试中。

难度: hard

标签: interviewbit, dbms, topic-specific, database

参考答案摘要

Selectivity refers to how unique the values in a column are. High selectivity means most values are unique, like user IDs. Low selectivity means many rows share the same value, like status flags. Inde...

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