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Index failure conditions

Index failure conditions (or index invalidation) refer to specific scenarios in database query execution where an existing index cannot be utilized, forcing the database to perform a full table scan.^[600-developer-mysql.md, 600-developer__mysql.md]

Function-based operations

Performing mathematical or logical operations directly on an indexed column within the WHERE clause typically prevents the index from being used.^[600-developer-mysql.md, 600-developer__mysql.md] For example, in a query like WHERE a + 1 = 5, the database cannot efficiently use the index on column a because the value of a must be modified before comparison.^[600-developer-mysql.md, 600-developer__mysql.md]

  • [[MySQL]]
  • [[Query optimization]]
  • [[Database indexing]]

Sources

  • 600-developer-mysql.md
  • 600-developer__mysql.md