Speculative query execution in Relational databases with Graph Modelling

In computer architecture, speculative execution is the process of executing instructions ahead of their normal schedule[1]. Grama et al.[2] introduce the concept of speculative decomposition as a possibility to execute one or more of possible branches in parallel with computation which are expected to determine the branch choice. The following paper introduces the method of speculative query execution in relational databases. Query queue can be seen as a line of sequential instructions and thus changing their order can result in some errors. Author introduce a middleware called the Speculative Layer which, based on a specific graph representation, executes some additional Speculative Queries. Results of those Speculative Queries can be used while executing queries from the queue providing a befit which is a shorter response time. The paper describes the process of graph modelling for groups of queries in order to initiate speculative computations, metrics used to evaluate Speculative Queries and experimental results for a test database and a group of input queries.