Microsoft Technology Licensing, LLC

Anshuman Dutt

Surajit J Chaudhuri

Vivek Ravindranath Narasayya

Chi Wang

Kapil Eknath Vaidya

The present disclosure relates to systems, methods, and computer-readable media for optimizing selection of a cached execution plan to use in processing a parametric query. For example, systems described herein involve training a plan selection model that makes use of machine learning to identify an execution plan from a set of pre-selected execution plans based on predicted cost of executing a query instance in accordance with the selected execution plan (e.g., relative to predicted costs of executing the query instance using other pre-selected execution plans). This application describes features related to lowering costs associated with selecting the execution plan in a way that will continue to be more accurate overtime based on training and refining the plan selection model.

Using query logs to optimize execution of parametric queries

A model generator constructs a model for estimating selectivity of database operations by determining a number of training examples necessary for the model to achieve a target accuracy and by generating approximate selectivity labels for the training examples. The model generator may train the model on an initial number of training examples using cross-validation. The model generator may determine whether the model satisfies the target accuracy and iteratively and geometrically increase the number of training examples based on an optimized geometric step size (which may minimize model construction time) until the model achieves the target accuracy based on a defined confidence level. The model generator may generate labels using a subset of tuples from an intermediate query expression. The model generator may iteratively increase a size of the subset of tuples used until a relative error of the generated labels is below a target threshold.

Efficiently constructing regression models for selectivity estimation

In some embodiments, the disclosed subject matter involves a server query optimizer for parametric query optimization (PQO) to address the problem of finding and reusing a relatively small number of query plans that can achieve good plan quality across multiple instances of a parameterized query. An embodiment processes query instances on-line and ensures (a) tight, bounded cost sub-optimality for each instance, (b) low optimization overheads, and (c) only a small number of plans need to be stored. A plan re-costing based approach is disclosed to provide good performance on all three metrics. Other embodiments are described and claimed.

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Redmond, WA, United States of America

Anshuman Dutt