Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for dynamic partition selection. One of the methods includes receiving a representation of a query plan generated for a query, wherein the query plan includes a dynamic scan operator that represents a first computing node obtaining tuples of one or more partitions of a table from storage and transferring the tuples to a second computing node that executes a parent operator of the dynamic scan operator. A partition selector operator is generated corresponding to the dynamic scan operator. A location in the query plan is determined for the partition selector operator. A modified query plan is generated having the partition selector operator at the determined location.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for dynamic partition selection. One of the methods includes receiving a representation of a query plan generated for a query, wherein the query plan includes a dynamic scan operator that represents a first computing node obtaining tuples of one or more partitions of a table from storage and transferring the tuples to a second computing node that executes a parent operator of the dynamic scan operator. A partition selector operator is generated corresponding to the dynamic scan operator. A location in the query plan is determined for the partition selector operator. A modified query plan is generated having the partition selector operator at the determined location.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for dynamic partition selection. One of the methods includes receiving a representation of a query plan generated for a query, wherein the query plan includes a dynamic scan operator that represents a first computing node obtaining tuples of one or more partitions of a table from storage and transferring the tuples to a second computing node that executes a parent operator of the dynamic scan operator. A partition selector operator is generated corresponding to the dynamic scan operator. A location in the query plan is determined for the partition selector operator. A modified query plan is generated having the partition selector operator at the determined location.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for dynamic partition selection. One of the methods includes receiving a representation of a query plan generated for a query, wherein the query plan includes a dynamic scan operator that represents a first computing node obtaining tuples of one or more partitions of a table from storage and transferring the tuples to a second computing node that executes a parent operator of the dynamic scan operator. A partition selector operator is generated corresponding to the dynamic scan operator. A location in the query plan is determined for the partition selector operator. A modified query plan is generated having the partition selector operator at the determined location.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for generating query plans for queries that include common table expressions. One of the methods includes receiving a query that includes a common table expression (CTE), wherein the CTE signifies that a system can compute a result for the query using a query plan that includes a CTE producer operator and a corresponding CTE consumer operator. A first query plan that includes a CTE producer operator and a corresponding CTE consumer operator and a second query plan that inlines an instance of the CTE consumer operator are generated. Respective costs are computed for the first query plan and the second query plan, and a result for the query is computed using the second query plan if the second query plan has a lower cost.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for generating query plans for queries that include common expressions. One of the methods includes receiving an initial query plan generated for a query that includes multiple common expressions; identifying two or more matching subtrees of the initial query plan; generating an alternative query plan that includes a CTE producer operator and having an instance of one of the matching subtrees as one or more descendant operators of the CTE producer operator, including replacing at least one instance of a matching subtree in the initial query plan with a CTE consumer operator corresponding to the CTE producer operator; computing respective costs for the initial query plan and the alternative query plan; selecting the alternative query plan based on the cost for the alternative query plan; and computing a result for the query using the alternative query plan instead of the initial query plan.

Abstract: A method, system, and computer program product for managing database statistics are provided. The method, system, and computer program product provide for receiving a query for optimizing, collecting statistics specific to the query prior to generating any access plans for executing the query, and generating an access plan for executing the query based on the collected statistics.

Abstract: A workload to be handled by a database system can be identified. The workload can include at least one query that the database system is to handle. A set of at least one candidate statistical views (statviews) to be utilized when optimizing the workload can be enumerated. A benefit value and a cost value of the each of the enumerated candidate statistical views relative to the entire workload can be computed. The cost value can reflect a cost of constructing and collecting statistics on the associated statistical view. A set of the candidate views most beneficial for handling the workload can be determined based upon the computed benefit values and computed cost values. A generalization phase that augments the candidate view set with higher value candidate views for consideration during the recommendation phase. The optimum subset of views from the determined set of candidate views can be recommended, which can cause them to be constructed and utilized by a database optimizer.

Abstract: A method, system, and computer program product for managing database statistics are provided. The method, system, and computer program product provide for receiving a query for optimizing, collecting statistics specific to the query prior to generating any access plans for executing the query, and generating an access plan for executing the query based on the collected statistics.