中文摘要：

从数据管理中的近似查询方向,对图数据的近似查询算法进行了研究。依据近似查询的类别,分别介绍了近似查询中的经典算法,并对这些算法进行了详细的分析和讨论,从索引单元以及索引机制比较了各种算法适用的范围以及应用领域。重点阐述和比较了各算法的特点及查询性能,分析了各个算法存在的优势和不足。对近似查询中现有算法的不足及未来的研究方向进行了讨论。

英文摘要：

From the approximate queries of data management, some representative algorithms in similarity search are reviewed. The algorithm based on their styles is classified and some classic algorithms from index unit and scheme in this area are presented. Some typical algorithms are investigated. Each algorithm＇s characteristic and search efficency are compared and refined to clarify their advantages and disadvantages. The comparison is given based on the properties of the algorithms and applications. Then the disadvantages and future research directions are discussed.