However, processing selection statements with complex conditions may involve a larger number of disk block accesses and in some cases complete scanning of the table. Hash Index − If hash indexes are used and its key field is used in the selection condition, then retrieving tuples using the ...
A mechanism is provided for generating statistical information for query optimization in a data processing system. The mechanism comprises a first database engine maintaining a current first dataset currently being stored, a second database engine maintaining a second dataset. The second dataset is ...
[12] G. Graefe. Encapsulation of Parallelism in the Volcano Query Processing System. In SIGMOD, 1990. [13] G. Graefe. The Cascades Framework for Query Optimization. IEEE Data Eng. Bull., 18(3), 1995. [14] G. Graefe and W. J. McKenna. The Volcano Optimizer Generator: Extensibility a...
由于SQL是声明式语言(declarative),用户只告诉了DBMS想要获取什么,但没有指出如何计算。因此,DBMS需要将SQL语句转换成可执行的查询计划(Query Plan)。但是对同样的数据可以有多种查询方案,性能也差距很大,查询优化器(Query Optimizer)的任务就是从给定的查询中选择一个最优的方案。 最早的查询优化器实现是IBM在1970s...
Additionally, the diverging mathematical foundations of data processing and machine learning hinder cross-optimizations by combining these two components, thereby overlooking potential opportunities to expedite predictive pipelines. In this paper, we propose an operator fusion method based on GPU-accelerated ...
mpp query optimization 一Query 1 Parsing 代码语言:javascript 代码运行次数:0 运行 AI代码解释 ParserQueryparser(end,settings.enable_debug_queries);ASTPtr ast;//把Query转化为抽象语法树ast=parseQuery(parser,begin,end,"",max_query_size); ASTPtrtryParseQuery(){//Token为lexer词法分析后的基本单位,...
an optimization problem where, given a workload of queries, we select a stratified random sample of the original data such that the error in answering the workload queries using the sample is minimized. A key novelty of our approach is that we can tailor the choice of samples to be robust...
Cloud computing is having a major impact on data management, with a proliferation of new, scalable data management solutions such as distributed file and object storage, NoSQL databases and big data processing frameworks. This also leads to a wide diversification of DBMS interfaces and the loss of...
Abstract We present a relational schema that stores the computations of a shared query evaluation plan, and tools that search the common computations between new queries and the schema, which are the two essential parts of the Incremental Multiple Query Optimization (IMQO) framework we proposed to...
1. A computer system, the computer system including a processing unit, a user input device coupled to the processing unit and display device coupled to the processing unit, the computer system also including: a user interface element comprising instructions executed by the processing unit, the user...