Multi-path cross-class query and optimization method in object agent database

Abstract

The invention provides a multi-path cross-class query and optimization method in an object proxy database, which comprises the following steps of: respectively obtaining queries of target attributes by using different path expressions on the same path, and defining the queries as multi-path cross-class queries with the same end point class; for the condition that a plurality of paths in the cross-class queries contain public class nodes, defining the paths as multi-path cross-class queries with different end point classes; then proposing multi-path cross-class query grammar support implementation for supporting multi-path cross-class queries with the same terminal class and different terminal classes; and finally, proposing an execution scheme of the multi-path cross-class querjes, and proposing a multi-path pointer tracking algorithm for the multi-path cross-class queries on the basis according to a pointer tracking algorithm thought used by the original cross-class query, wherein themulti-path pointer tracking algorithm is used for calculating a multi-path expression. By adopting the method and the device, a user can obtain different target attribute expressions by using one path expression, redundant expressions of the common path expression are reduced, and the query efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of database query optimization, in particular to a multi-path cross-class query and optimization method in an object proxy database. Background technique [0002] With the rapid development of cloud computing and big data technology, database applications are constantly updated, and new application fields provide new directions for the development of database technology, and also put forward new requirements. Massive data is no longer limited to structured patterns, and semi-structured, unstructured, and other complex-structured data have emerged. The traditional relational data model mainly manages structured data, so it seems stretched to face this situation. The object-oriented database proposes a management scheme for complex data, but because it uses encapsulation to manage semi-structured and unstructured data, it makes it difficult to move, split and reorganize objects, so it loses the unique flexibi...

AI Technical Summary

Problems solved by technology

[0006] (1) When the query contains multiple path expressions with common parts, independent execution between multiple path expressions will cause a large number of repeated accesses to objects

For this kind of demand for obtaining attributes in different objects in the same object network, there is currently a lack of a query function that enables users to obtain different target attributes by writing only one path expression

[0007] (2) Currently in ODDB, since multiple path expressions need to be used to obtain target attribute values ​​independently of each other, and the "real-time calculation" mode of one object at a time is adopted, when the queried proxy class has a higher proxy level, multiple There are relatively many public class nodes between the two paths, and there are a lot of repeated access to objects in the public class when obtaining the target attribute

Repeated access to objects requires repeated scanning of the bidirectional pointer table. Frequent access will result in a large number of I / O operations, which seriously affects the efficiency of cross-class queries

Images