| 摘要 |
The present invention extends to methods, systems, and computer program products for optimizing parallel queries using interesting distributions. For each logical operator in an SQL server MEMO, in a top down manner from a root operator to the leaf operators, interesting distributions for the operators can be identified based on the properties of the operators. Identified interesting distributions can be propagated down to lower operators by annotating the lower operators with the interesting distributions. Thus, a SQL server MEMO can be annotated with interesting distributions propagated top down from root to leaf logical operators to generate an annotated SQL server MEMO. Parallel query plans can then be generated from the annotated SQL server MEMO in a bottom up manner from leaf operators to a root operator. Annotated interesting properties can be used to prune operators, thereby facilitating a more tractable search space for a parallel query plan. |
| 主权项 |
1. At a computer system, the computer system including one or more processors and system memory, the computer system connected to a plurality of compute nodes configured in a shared-nothing architecture, a distributed database distributed across the plurality of compute nodes, each compute node in the plurality of compute nodes maintaining a portion of the database in a local database instance, a method for identifying and propagating interesting properties within a SQL Server MEMO, the method comprising:
accessing a SQL Server MEMO for a query of the distributed database, the SQL Server MEMO including a plurality of groups of logical operators arranged in a hierarchically structure, the hierarchical structure including a root group, one or more intermediate groups, and one or more leaf groups, each group of logical operators including one or more logical operators on one or more input groups; and for each of the plurality of groups, starting at the root group and in a top down manner:
identifying interesting distributions relevant to any child groups of the group; andadding the identified interesting distributions to the child groups by annotating the child groups with the interesting distributions.
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