OPTIMIZING PARALLEL QUERIES USING INTERESTING DISTRIBUTIONS

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. A computer system, the computer system comprising:
one or more processors; system memory; and a distribution identifier, using one of the one or more processors, configured to:
access a query plan search space for a query of a distributed database; andformulate an annotated query plan search space, including:
for a group of logical operators in the query plan search space, identify a distribution property indicating an interesting type of distribution relevant to the group, the distribution property identifying a column that data for a parent group of the group is distributed on; andannotate the group with the interesting type of distribution by attaching an indication of the identified column to the group to propagate the identified interesting type of distribution to the group for use in subsequent query plan pruning.