Compression and decompression method for ROWID corresponding relation data

A technology of correspondence and compression methods, applied in database indexing, structured data retrieval, special data processing applications, etc., can solve problems such as insufficient speed and unsatisfactory compression effect, and achieve fast execution speed, high compression rate, and algorithmic simple effect

Active Publication Date: 2019-11-01
INFORMATION2 SOFTWARE SHANGHAI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The mapping block needs to occupy a certain amount of space, but it has a lot of the same or similar data, the target SLOT is often continuous, the target OBJD is usually the same value, and the target DBA is also easy to repeat, so there is a lot of space for compression in storage , since its query will be very frequent, the speed of compression and decompression should be faster
Existing compression algorithms such as zip and minilzo are not fast enough and the compression effect is not ideal

Method used

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  • Compression and decompression method for ROWID corresponding relation data
  • Compression and decompression method for ROWID corresponding relation data
  • Compression and decompression method for ROWID corresponding relation data

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Embodiment Construction

[0046] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described below through specific embodiments and accompanying drawings.

[0047] This embodiment discloses a method for compressing ROWID correspondence data, such as image 3 The flow chart shown specifically includes the following steps:

[0048] 1) Define the marker byte, which is abbreviated as FLG below. Each piece of compressed data starts with a FLG. The 8 bits of FLG have different purposes:

[0049] Bit 7: The source SLOT has no record flag bit, if this bit is set, the other 7 bits represent how many consecutive SLOTs have no record.

[0050] Bit 6: Whether the target SLOT occupies 1 byte or 2 bytes.

[0051] Bit 5: New target DBA flag, setting this bit means that a new DBA has been encountered, and the compressed data contains a 4-byte DBA; otherwise, it means that a used DBA has been encountered, and the...

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Abstract

The invention provides a compression and decompression method for ROWID corresponding relation data. The method belongs to the field of computer ORACLE database synchronization, the characteristics ofdata in mapping blocks are fully utilized, flag bytes FLG are set, whether SLOT is recorded or not, whether DBA is repeated or not, whether OBJD is repeated or not and whether ROWID is continuous ornot are judged one by one, compression is achieved, and decompression is achieved by judging whether bits of FLG are set or not. The method is simple in algorithm and high in execution speed, and hasa very high compression ratio for ROWID mapping data with high continuity.

Description

technical field [0001] The invention belongs to the field of computer ORACLE database synchronization, in particular to a method for compressing and decompressing ROWID corresponding relationship data. Background technique [0002] The ORACLE database is a very widely used database. Each row of records stored in the ORACLE database has a unique identifier called ROWID, and this record can be queried with ROWID. [0003] ROWID is divided into three parts, OBJD, DBA and SLOT, a total of 10 bytes. OBJD occupies 4 bytes, which is the unique number assigned by the ORACLE database to each table, partition or sub-partition of the table; DBA is the number of the data block, which occupies 4 bytes, and ORACLE stores records in different data blocks; a data Multiple records can be stored in a block. The ROWID of all records in the same data block, their OBJD and DBA are the same, and the number recorded in the block is called SLOT, which occupies 2 bytes. [0004] For the convenienc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F16/22H03M7/30
CPCG06F16/2228H03M7/30
Inventor 高志会李天伟林广生
Owner INFORMATION2 SOFTWARE SHANGHAI
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