how database index works

Turn from: 51333169Let's start the tutorial with a simple example that explains why we need a database index. Let's say we have a database table Employee, and this table has three fields (columns), Employee_Name, Employee_age, and employee_address,

Database storage structure: page, clustered index, nonclustered indexTo understand the database storage structure, understand how the database is accessed first and then understand the database storage structure in principle.I. How data is accessed

Start from Create By using the explicit CREATE INDEX command As an implied object when creating a constraint Implicit indexes created with constraintsAn implicit index is created when you add one of the following two constraints to

The main considerations for designing SQL Server indexes are as follows:Check where condition and join condition column;Use narrow index;Check the selectivity of the column;Check the data type of the column;Consider the order of the columns;Consider

The main considerations for designing SQL Server indexes are as follows:Check where condition and join condition column;Use narrow index;Check the selectivity of the column;Check the data type of the column;Consider the order of the columns;Consider

The main considerations for designing SQL Server indexes are as follows:Check where condition and join condition column;Use narrow index;Check the selectivity of the column;Check the data type of the column;Consider the order of the columns;Consider

Because of the invisible nature of the index, many people may also be confused about how it works, so they often don't know how to start indexing.Some basic concepts:1. Data page: see Indexing principle. In a clustered index, it is the leaf node of

This article describes the principles of fragmentation in SQL Server, the concepts of internal fragmentation and external fragmentation. And the methods of solving the fragmentation and filling factors. In the database, often every feature that is

Type of index:Normal: Indicates normal indexUnique: Represents a unique, not allowed duplicate index, if the field information is guaranteed not to be duplicated such as a social security number used as an index, can be set to a uniqueFull TEXTL:

This article describes the principles of fragmentation in SQL Server, the concepts of internal fragmentation and external fragmentation. And the methods of solving the fragmentation and filling factors. In the database, often every feature that is