Bitmap index compressing method and bitmap index decompressing method

A technology of bitmap index and compression method, which is applied in the database field, can solve the problems of increasing the complexity of bitmap index decompression, affecting the efficiency of bitmap index retrieval and query, and increasing the storage space of bitmap index, so as to improve the efficiency of retrieval and query, Reduce the complexity of decompression and the effect of reducing storage space

Active Publication Date: 2014-08-20
SHANGHAI DAMENG DATABASE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The defect of the above-mentioned bitmap index compression technique is that although the number of 0s in front of each 1 can be recorded in binary with the corresponding number of digits, the storage space for the number of 0s in front of each 1 can be reduced, but adding The control information of the bitmap index will increase the storage space of the bitmap index; and the complex encoding method increases the decompression complexity of the bitmap index, thus affecting the retrieval efficiency of the bitmap index

Method used

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  • Bitmap index compressing method and bitmap index decompressing method
  • Bitmap index compressing method and bitmap index decompressing method
  • Bitmap index compressing method and bitmap index decompressing method

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Embodiment 1

[0033] see figure 1 , is a flowchart of a bitmap index compression method provided in Embodiment 1 of the present invention. The method in the embodiment of the present invention can be executed by a bitmap index compression device implemented by hardware and / or software, and the implementation device is typically configured in a server capable of providing bitmap index compression services. Such as figure 1 As shown, the method includes:

[0034] Step 110, for the bitmap index of the index key contained in the pre-established data base table, segment the bitmap index according to the preset segment width to obtain multi-segment bitmap information;

[0035] The data base table is an important object in the database and consists of various elements. The index keywords contained in the data base table represent the values ​​of the elements contained in the attributes of each column in the data base table. Bitmap index is a special database indexing technology using bitmap. I...

Embodiment 2

[0075] see figure 2 , is a flow chart of a bitmap index compression method provided in Embodiment 2 of the present invention. Such as figure 2 As shown, the method includes:

[0076] Step 210, for the bitmap index of the index key contained in the pre-established data base table, segment the bitmap index according to the preset segment width to obtain multi-segment bitmap information;

[0077] Step 220, for each piece of bitmap information, determine the sparse factor of the current piece of bitmap information;

[0078] In this step, when the effective value is 1, the thinning factor is the ratio of the number of 0s in the current segment bitmap information to the preset segment width; when the effective value is 0, the thinning factor is the current segment bitmap information The ratio of the number of 1s to the preset segment width.

[0079] Step 230, judging whether the sparse factor of the current segment bitmap information is greater than or equal to the preset spar...

Embodiment 3

[0092] see image 3 , is a flowchart of a bitmap index compression method provided in Embodiment 3 of the present invention. Such as image 3 As shown, the method includes:

[0093] Step 310, for the bitmap index of the index key contained in the pre-established data base table, segment the bitmap index according to the preset segment width to obtain multi-segment bitmap information;

[0094] Preferably, the preset segment width is an integer multiple of 8.

[0095] Step 320, for each segment of bitmap information, determine the first auxiliary information of the segment of bitmap information;

[0096] Wherein, the first auxiliary information includes at least the start line number of the bitmap information segment and the end line number of the bitmap information segment. The first auxiliary information may also include a segment number. The end line number is related to the start line number and the preset segment width.

[0097] For example, if the bitmap index of the...

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Abstract

The embodiment of the invention provides a bitmap index compressing method and device. Bitmap information of segments of bitmap indexes corresponding to an index key word is obtained according to preset segment width segments, deviation values of effective values of the bitmap information of the segments are stored according to the corresponding binary storage digits, compression information of the bitmap information of the segments is obtained, and due to the fact that only the deviation values of the effective values in the bitmap information of the segments are stored, storage space of the bitmap indexes can be reduced. Correspondingly, the embodiment of the invention provides a bitmap index decompressing method and device, storage bits of binary representation information of the deviation values of the effective values are utilized for obtaining the deviation values of the effective values in the compression information of the bitmap information of the segments, the bits corresponding to the deviation values of the effective values in initialized bitmap information are arranged to be the effective values, decompression information corresponding to the compression information of the bitmap information of the segments is obtained, the decompression complexity of the bitmap indexes can be reduced, and the searching query efficiency of the bitmap indexes is improved.

Description

technical field [0001] The embodiment of the present invention relates to the technical field of databases, in particular to a bitmap index compression method and a bitmap index decompression method. Background technique [0002] With the rapid development of computer information technology, more and more users have put forward higher requirements for the storage and retrieval of massive data. The bitmap index corresponds to the index key in the data base table. The application of the bitmap index on massive data is common. For example, the bitmap index is used to retrieve the sales of a certain product in a certain period of time on the data base table. Wait. While improving bitmap index retrieval performance, the requirement for bitmap index storage space is getting higher and higher, so bitmap index compression technology emerges as the times require. [0003] The existing bitmap index compression technology generally calculates the number of 0s before each 1 in the bit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/30
CPCG06F16/2237
Inventor 彭青松朱仲颖汪龙重
Owner SHANGHAI DAMENG DATABASE
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