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What is index (database) ?

We can use index to access the specific information quickly in database table. In database, index is a data structure, which orders data of one or more columns in database table. For example, name column in an employee table, if a developer wants to search specific staff with name, and compared it with table, index can help the developer access the information more quickly.

Index is a database structure. It can be created by using one or more columns of a database table, providing the basis for both rapid random look ups and efficient access of ordered records.

Index could provide the data pointer that specified to the data value set which is stored in specified column, and then order these pointers according to the specified sort order. Index in database is very similar to the index in using books: it searches index and finds out the special value, then finds out the column in this value following with the pointers.

In a relational database an index is a copy of part of a table. In "INDEX/KEY" property page of the selected table, developer can CREATE, EDIT, or DELETE the type of each index. Indexes may be defined as unique or non-unique. A unique index acts as a constraint on the table by preventing duplicate entries in the index and thus, the backing table. When stored the index to the attach table or stored in relational graph where the table is, index will be stored in the database.

Tag: Index,relational database,table,seach data,database structure

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