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A method for reconstructing a mixed index with storage perception

A storage-aware and indexing technology, applied in the field of database query, can solve problems such as low indexing efficiency, and achieve the effect of good practicability and versatility, efficiency and space occupancy balance

Active Publication Date: 2019-01-29
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a method for reconstructing a storage-aware hybrid index based on the deficiency of the above-mentioned background technology, improve the index structure based on the FD-tree, determine the internal and external memory distribution of the index tree based on the memory space, and store the Part or all of the index structure on the hard disk is imported into the main memory to improve query and update efficiency without destroying the persistence characteristics of the system. It solves the problem of importing only the B+-tree at the top of the index tree into the main memory. There is a technical problem with low indexing efficiency

Method used

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  • A method for reconstructing a mixed index with storage perception
  • A method for reconstructing a mixed index with storage perception
  • A method for reconstructing a mixed index with storage perception

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Embodiment 1

[0045] Embodiment 1: The index creation and reconstruction process, the specific steps are as follows image 3 , Figure 6 shown, including:

[0046] 1. Index creation

[0047] A. Obtain the continuous space that can be occupied by the memory, calculate the space occupied by the index structure according to the number of key values, and initialize the hierarchical address table:

[0048] First calculate the space occupied by using the top-level tree completely. If it exceeds the threshold (according to the memory occupancy calculation*50%), then calculate the space occupied by the optimal number of layers of the B+-tree, and the remaining layers use the ordered index item sequence layer to calculate separately Layer number and hierarchical address table;

[0049] B. Create an initial index file of the appropriate size:

[0050] The index file is the file that stores the entire index structure and is located in the external memory. The purpose of the index file is that when...

Embodiment 2

[0070] Embodiment 2: five operations including insertion, deletion, point query, range query and modification of the index are as follows:

[0071] 1. point query operation

[0072] A. Search in the top layer to find the corresponding leaf node;

[0073] B. Perform key-value comparison within the node;

[0074] C. If the corresponding key value is found, determine whether it is an index item, and if so, return the corresponding row identifier;

[0075] D. If it is an item to be deleted, the key value does not exist, the query fails and returns; otherwise, the corresponding child node offset is obtained;

[0076] E. If the corresponding key value is not found, find the largest pointer item smaller than it and obtain the offset of the child node;

[0077] F. Access the child node according to the node read and write method based on overflow detection;

[0078] G. Repeat steps B-E until reaching the bottom node;

[0079] H. If the key value exists in the node, return the co...

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Abstract

The invention discloses a method for reconstructing a mixed index with storage perception, belonging to the technical field of database query. The hybrid index structure is divided into top layer in main memory, middle layer in memory and bottom layer in external memory. The top layer and middle layer are all stored in memory when there is enough memory, and the middle layer is stored in externalmemory when there is not enough memory. The invention also discloses a method for creating a mixed index structure, a read method, a range query method, and a reconstruction method store part of indexdata in external storage when memory is insufficient through memory mapping length, effectively utilize storage resources such as memory and external storage, and can reasonably decide the proportionof internal and external storage of index structure according to system conditions or user efficiency requirements, and improve query efficiency.

Description

technical field [0001] The invention discloses a method for reconstructing a hybrid index with storage awareness, belongs to the technical field of database query, and is a divisional application of the invention patent with application number 201510310349.X, and the application date of the parent application is June 8, 2015. Background technique [0002] The existing database index can be divided into two types according to the storage method. One is to use the frequent access method completely based on the hard disk to perform query and other operations, but does not make full use of the faster processing devices such as main memory and cache, and the performance cannot break through the device. bottleneck. The other is the main memory index technology, that is, the index is completely built in the main memory. As an efficient index method, caching technology is often used, and the performance is very efficient under the framework of modern computers. However, when the amo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F16/22
CPCG06F16/2228G06F16/2272
Inventor 秦小麟王胜史文浩王潇逸李博涵
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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