Oracle Index: What It Is & How to Create

An index is a data structure that can improve the performance of retrieving data from a database. It is a pointer that indicates the position of data in a table, assisting the database engine in locating and retrieving data more quickly.

You can use the CREATE INDEX statement in Oracle database to create an index. The syntax is as follows:

CREATE INDEX index_name
ON table_name (column1, column2, ...);

In this case, index_name represents the name of the index, table_name refers to the name of the table where the index is to be created, and column1, column2, etc. are the names of the columns to be included in the index.

For example, to create an index for the salary column in a table named employees, you can use the following statement:

CREATE INDEX salary_index
ON employees (salary);

After creating an index, you can use it in queries to speed up data retrieval. It’s important to note that while indexes can improve retrieval performance, they can also increase the overhead on write operations in the database. Therefore, when creating an index, it is necessary to carefully consider the trade-offs based on the actual situation.