In the database physical design phase, what is the purpose of creating indexes for data tables?

In the database physical design stage, the purpose of creating indexes for data tables is to improve query retrieval capabilities and improve query efficiency. An index is a structure that sorts the values ​​of one or more columns in a data table. Creating an index can greatly improve the speed of obtaining the required information in the database, and also improve the efficiency of the server in processing related search requests.

The operating environment of this tutorial: windows7 system, mysql8 version, Dell G3 computer.

In the database physical design stage, the purpose of creating indexes for data tables is to improve query retrieval capabilities and improve query efficiency.

An index is a structure that sorts the values ​​of one or more columns in a database table. Indexes can be used to quickly access specific information in a database table. If you want to find a specific employee by his or her last name, an index can help you get the information faster than searching for all the rows in the table.

One of the main purposes of the index is to speed up the retrieval of data in the table, that is, an auxiliary data structure that can help information searchers find record IDs that meet the restrictions as quickly as possible.

Creating indexes can greatly improve system performance. First, by creating a unique index, the uniqueness of each row of data in the database table can be guaranteed. Second, it can greatly speed up data retrieval, which is also the main reason for creating an index. Third, it can speed up the connection between tables, which is particularly meaningful in achieving referential integrity of data. Fourth, when using grouping and sorting clauses for data retrieval, the time for grouping and sorting in queries can also be significantly reduced. Fifth, by using indexes, optimization hiders can be used during the query process to improve system performance.

Because there are many disadvantages to increasing indexes. First, creating and maintaining indexes takes time, and this time increases as the amount of data increases. Second, indexes need to occupy physical space. In addition to the data space occupied by the data table, each index also occupies a certain amount of physical space. If a clustered index is to be established, the space required will be larger. Third, when adding, deleting, and modifying data in the table, the index must be dynamically maintained, which reduces the data maintenance speed.

Related free learning recommendations: mysql video tutorial

The above is the detailed content of In the database physical design phase, what is the purpose of creating indexes for data tables?. For more information, please follow other related articles on the PHP Chinese website!