Index - Unique Index

Data System Architecture


A unique index is an index data structure that:

  • does not allow duplicate
  • allows Null value
  • implements a unique key.

If the key is already present, it will reject the insertion by throwing an error.


This kind of structure are generally implemented with a hashmap.

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Logical Data Modeling - Unique Key

A Unique Key identifies: the lowest level of an entity the unique identifier of a single instance remains unique over time butcan change over time. and enforces uniqueness primary key The set...
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Unique key implementation in a relational environment A unique constraint is a constraint that enforces the Entity Integrity e.g. that every value in a column or set of columns (key) be unique—that...

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