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  • SQL Selectivity

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    Selectivity

    Selectivity is used for the definition of the number of unique values in the table.

    It shows how many unique values are there in the table.

    Selectivity=Cardinality/number of record *100%

    If the selectivity is high than only the database index is used.

    There are many unique values that means the selectivity of the table is high.

    It means there is need of index.

    Selectivity then basically is used as query optimizer to get that if index applied to the table can be efficient or not

    or reading the full table would do the work.

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