Data base indexing process

A database and indexing technology, which is applied in the field of database indexing, can solve the problems of increasing demand for index files, aggravating the degree of space waste, wasting overflow page space, etc., and achieve the effect of broadening the scope of application, reducing size, and avoiding space waste

Inactive Publication Date: 2008-10-15
TONGJI UNIV
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Problems solved by technology

[0004] Although this method is simple, it inevitably wastes the free space in the overflow page, especially when the space occupied by the key value is smaller than the capacity of the overflow page, the degree of space waste is intensified, and the demand for the entire index file on the disk increases accordingly. obviously increase

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Embodiment Construction

[0026] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0027] see figure 1 , the present invention discloses a method for database indexing, characterized in that the method comprises the following steps:

[0028] Step A, building a B+ tree according to the index database;

[0029] Step B, define the data structure of the B+ tree in step A, and store repeated key values ​​in the leaf nodes of the B+ tree; including:

[0030] Step B1, redefining the index key value of the B+ tree non-leaf node; defining the i-th index key value in the B+ tree non-leaf node as: in the subtree rooted at the i+1th child node of the non-leaf node , the new key value that appears for the first time; if the new key value does not exist, that is, all the key values ​​contained in the subtree are the same and have appeared in the previous subtree, define the index key value as "empty ".

[0031] Step B2, adding an ind...

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Abstract

The invention discloses a method for database index, comprising the steps as follows: step A. a B+ tree is established according to the index database; step B. a data structure of the B+ tree in the step A is defined, repeated key assignments are stored in leaf nodes of the B+ tree; step C. index operations are executed, the index operations comprise query operation, insertion operation and deletion operation. The database index method of the invention which uses the B+ tree avoids using overflow nodes as repeatedly appeared key assignments are directly stored in the leaf nodes of the B+ tree; therefore, the method of database index has the advantages of avoiding the spacial waste effectively, reducing the size of the index documents and expanding the application range of the B+ tree when overflow nodes are larger than key assignments and a datasheet has a plurality of repeated key assignments, thus optimizing the database index proposal.

Description

technical field [0001] The technical field of database indexing of the present invention relates to a database indexing method, in particular to a database indexing method using a B+ tree. Background technique [0002] B-tree was proposed by R.Bayer and E.McCreight in 1972. It can be regarded as the general form of multi-way expansion of "binary search tree" in external memory. It is designed to manage and maintain large-scale data indexes. It has It has the characteristics of high random query efficiency, low update overhead and self-balancing. Based on the B-tree, the B+ tree further stipulates that all "key values" can only appear in the leaf nodes, and connects all the leaf nodes together in the form of a linked list, which improves the efficiency of sequential query. [0003] When studying the algorithm of B+ tree, for the sake of simplicity, it is generally assumed that there is no duplication of key values. The existing method for dealing with duplicate key values ​...

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Application Information

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IPC IPC(8): G06F17/30
Inventor 蒋昌俊曾国荪陈闳中苗夺谦闫春钢方钰徐逸文
Owner TONGJI UNIV
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