Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for precisely tracking memory usage in a multi-process computing environment. One of the methods includes implementing an instance of a memory usage tracker (MUT) in each process running in a node of a computer system. A MUT can maintain an account of memory usage for each of multiple logical owners running on a process on which the MUT is running. The MUT can determine an actual memory quota for each owner, and enforce the actual memory quota of the owner. Enforcing the actual memory quota of the owner can include receiving each memory allocation request, checking each allocation request and a current state of the account against the actual quota, approving or rejecting each allocation request, communicating the approval or rejection to an underlying memory manager, and updating the owner account for each approved allocation request.

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: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for precisely tracking memory usage in a multi-process computing environment. One of the methods includes implementing an instance of a memory usage tracker (MUT) in each process running in a node of a computer system. A MUT can maintain an account of memory usage for each of multiple logical owners running on a process on which the MUT is running. The MUT can determine an actual memory quota for each owner, and enforce the actual memory quota of the owner. Enforcing the actual memory quota of the owner can include receiving each memory allocation request, checking each allocation request and a current state of the account against the actual quota, approving or rejecting each allocation request, communicating the approval or rejection to an underlying memory manager, and updating the owner account for each approved allocation request.

Abstract: A reconfigurable web-browser compatible data query system. The invention provides an XML platform enabling web-based forms that query data modeled by data schemas. This platform comprises a collection of query form controls, an annotation scheme for attaching these controls to the data schema, a compiler for creating a web-browser-compatible representation of the query form, and a run-time engine for constructing queries against the data and rendering query results.

Abstract: A reconfigurable web-browser compatible data query system. The invention provides an XML platform enabling web-based forms that query data modeled by data schemas. This platform comprises a collection of query form controls, an annotation scheme for attaching these controls to the data schema, a compiler for creating a web-browser-compatible representation of the query form, and a run-time engine for constructing queries against the data and rendering query results.

Abstract: A reconfigurable web-browser compatible data query system. The invention provides an XML platform enabling web-based forms that query data modeled by data schemas. This platform comprises a collection of query form controls, an annotation scheme for attaching these controls to the data schema, a compiler for creating a web-browser-compatible representation of the query form, and a run-time engine for constructing queries against the data and rendering query results.