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Primary Key vs. Secondary Key?

General/Othereasy0.4 min readPremium
Frequency
Low
Asked at 1 company
Category
243
questions in General/Other
Difficulty Split
151E|43M|49H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Altimetrik
Expert AnswerPremium
71 wordsInterview-ready
PRIMARY KEY: Unique identifier; one per table; NOT NULL; used for FKs. SECONDARY KEY: Non-primary unique (e.g., email, passport); can have multiple; supports lookups. WHY: PK enables referential integrity; secondary keys support alternate access paths. SCALABILITY: Index on PK is default; secondary keys need explicit indexes. COST: More indexes = slower writes, more storage; choose based on query patterns....
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