Tutorial by Topics: indexes



Indexes are a data structure that contains pointers to the contents of a table arranged in a specific order, to help the database optimize queries. They are similar to the index of book, where the pages (rows of the table) are indexed by their page number.

Several types of indexes exist, and can be created on a table. When an index exists on the columns used in a query's WHERE clause, JOIN clause, or ORDER BY clause, it can substantially improve query performance.

Here I will explain different index using example, how index increase query performance, how index decrease DML performance etc


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