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Database repeatable reading implement method, device and database management system

An implementation method and management system technology, applied in the direction of electrical digital data processing, special data processing applications, instruments, etc., can solve the problems of damaging transaction concurrency and sacrificing system performance, and achieve the goal of increasing transaction concurrency and improving system performance Effect

Inactive Publication Date: 2010-04-21
ZTE CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The easiest way to resolve conflicts is to use a lock mechanism. Before reading or writing, add an intentional shared lock or intentional exclusive lock to the table, add a shared lock or exclusive lock to the record, but this damages the concurrency of the transaction and sacrifices the system. performance

Method used

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  • Database repeatable reading implement method, device and database management system
  • Database repeatable reading implement method, device and database management system
  • Database repeatable reading implement method, device and database management system

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Embodiment Construction

[0045] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments to further understand the purpose, scheme and effect of the present invention, but it is not intended to limit the protection scope of the appended claims of the present invention.

[0046] refer to figure 1 , describe in detail the implementation method of database repeatable reading of the present invention, the method is used in a multi-user, multi-transaction concurrent database management system, wherein, the system maintains a rollback segment, an index tree, a transaction list and a read view structure.

[0047] The implementation method of repeatable reading of the database includes:

[0048] Step S10, when traversing the transaction list maintained by the system, use the index to quickly locate the page that satisfies the conditions, wherein the transaction list is used to save the currently concurrently executing and uncommitted trans...

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Abstract

The utility model discloses an implementation method for the repeated read of database which is used for a multi-user and multiple transaction concurrency database management system which maintains atransaction list, a rollback segment and an index tree. The method comprises the following steps: firstly, the page satisfying conditions is quickly positioned utilizing the index when traversing thetransaction list maintained by the system, wherein the transaction list is used for storing the transaction which is concurrently executed and uncommitted; secondly, the current transaction is checkedwhen traversing the page record to found whether the current record is visible, the current record is added to the result set if the current record is visible; otherwise, the original version is constructed and added to the result set by utilizing the revocation log of the rollback segment maintained by the system, wherein the rollback segment is used for recording the modification of the transactions. The utility model also discloses an implementation apparatus utilizing the method and a database management system utilizing the method and the apparatus.

Description

technical field [0001] The invention relates to a database management system (DBMS), in particular to a transaction isolation level, especially a method and device for realizing repeatable reading of data when multiple transactions are concurrently executed, and a database management system using the same. Background technique [0002] Transactions in the database management system must ensure four attributes: atomicity, that is, all actions in the transaction are executed or not executed at all; consistency, that is, each transaction must maintain the consistency of the database; isolation, that is, the execution of each transaction Not affected by other transactions being executed; persistence, that is, once the transaction is successfully committed, all changes to the database should be persisted on the storage medium. [0003] There are transactions T1 and T2, and there may be three kinds of conflicts during concurrent execution: WR conflicts, that is, T2 may read the da...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/30
Inventor 印和平常二鹏李世亮卢勤元
Owner ZTE CORP
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