Can Oracle duplicate indexes?

Oracle cannot duplicate indexes. In the Oracle database, creating duplicate indexes is not allowed and will cause an error. Duplicate indexes may cause the following problems: 1. Waste of storage space, which will increase the storage requirements of the database and may lead to performance degradation; 2. Increase maintenance costs. When adding, deleting, or modifying operations on the table, the database needs to update all related indexes. , with duplicate indexes, the update operation will become more complex and time-consuming; 3. Reduced performance, with duplicate indexes, the database may select the wrong index, resulting in reduced query performance.

#The operating environment of this article: Windows 10 system, oracle11g version, Dell G3 computer.

Oracle does not allow duplicate indexes. In Oracle database, creating duplicate indexes is not allowed and will cause an error.

Index is a data structure used to improve database query performance. They allow quick access and location of specific data rows in database tables, thus speeding up query operations. An index is created based on the values ​​of one or more columns and organizes the data in a specific order. By using indexes, the database can avoid full table scans, thereby improving query efficiency.

Duplicate index refers to creating two or more indexes with the same columns on the same table. For example, if you create an index on column A in a table and then create another index on the same column A, then this is a duplicate index. Duplicate indexes may cause the following problems:

Wasted storage space: Duplicate indexes take up additional storage space because they store the same data. This increases the storage requirements of the database and may cause performance degradation.

Increase maintenance costs: Creating and maintaining duplicate indexes will increase the maintenance cost of the database. When adding, deleting or modifying a table, the database needs to update all related indexes. If duplicate indexes exist, update operations become more complex and time-consuming.

Reduced performance: Duplicate indexes will increase query overhead. When executing a query, the database needs to choose which index to use to improve performance. If duplicate indexes exist, the database may select the wrong index, resulting in poor query performance.

To avoid duplication of indexes, it is recommended to do some checking and planning before creating an index. You can use the tools provided by Oracle to view existing indexes and check whether there are duplicate indexes. If duplicate indexes are discovered, you can choose to delete one or more duplicate indexes to reduce storage requirements and maintenance costs.

In addition, you can also avoid duplicate indexes by merging indexes. Merging indexes means merging multiple indexes into a larger index. By merging indexes, you can reduce the number of indexes, thereby reducing storage requirements and maintenance costs. Merging indexes also improves query performance because the database only needs to search one larger index instead of multiple smaller indexes.

Summary

Oracle does not allow the creation of duplicate indexes. Duplicate indexes can result in wasted storage space, increased maintenance costs, and reduced query performance. To avoid duplication of indexes, it is recommended to check and plan before creating indexes and to use merged indexes to reduce the number of indexes.

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