Mcafee, Inc.

Tandem Computers Incorporated

Jay Vaishnav

E John Sebes

Rahul Roy-Chowdhury

Hansjorg Zeller

Pedro Celis

Goetz Graefe

Diana Shak

On a host, host content change requests are intercepted in real-time. In a tracking mode, the change requests are logged and allowed to take effect on the host. In an enforcement mode, the change requests are logged and additionally compared against authorized change policies and a determination is made whether to allow the change to take effect or to block the changes, thereby enforcing the authorized change policies on the host. Tracking and enforcement can be done in real-time. In either mode and at any time, the logged changes can be reconciled against a set of approved change orders in order to identify classes of changes, including changes that were deployed but not approved and changes that were approved but not deployed.

Enforcing alignment of approved changes and deployed changes in the software change life-cycle

A method is employed to group computers to facilitate application of a software modification to the computers. The method includes identifying a global set of computers to which it is desired to apply the software modification. Based on characteristics of software configurations of the computers of the identified global set, the computers of the identified global set are grouped into a plurality of clusters. Grouping the computers into a plurality of clusters includes processing syntactic information about the computers to identify the plurality of clusters and applying the software modification to the computers of the clusters. The software modification is applied with an adjustment for each cluster in an attempt to avoid software breakage of the computers of that cluster.

Software modification by group to minimize breakage

A system and method for optimizing a database query with improved performance enhancements is herein disclosed. The database query consists of one or more logical expressions. Through the repeated application of one or more rules, the logical expressions are transformed into execution plans. The query optimizer partitions the database query into one or more subproblems with each subproblem consisting of one or more logical expressions. A plan is obtained for each subproblem with the plan for the database query including the plans for each subproblem. The query optimizer is cost-based and uses rules including transformation and implementation rules that are used to perform transformations on the logical expressions in a subproblem in order to produce a plan. The rules are classified into context-free and context-sensitive in order to avoid generating duplicate expressions. Context-free rules are applied once for each logical expression and context-sensitive rules are applied once for each logical expression for a particular optimization goal. In a preferred embodiment, the query optimizer performs several optimization passes over the database query in order to obtain an optimal plan. For each pass, if no optimal plan exists for the requested optimization goal, existing plans having the same optimization goal are utilized with each input reoptimized for a more cost effective plan.

System and method for optimizing database queries with improved

A system and method for optimizing a database query is herein disclosed. The system consists of a search engine and a database implementor that determines an optimal plan for executing a SQL query. The SQL query is represented as a query tree consisting of a number of nested expressions. The search engine generates a number of plans from which an optimal plan is selected. Plans are generated through the application of a set of rules consisting of implementation and transformation rules. Implementation rules are used to obtain plans. Transformation rules are used to determine equivalent expressions. A plan for the query tree entails finding plans for each expression within the tree where each plan is generated in accordance with a prescribed set of rules. The database implementor selects the set of rules such that more promising plans are generated rather than generating all possible plans. In a preferred embodiment of the invention, multiple passes are made by the search engine in order to determine the optimal plan. In a first pass, implementation rules are used in order to generate a first plan having a cost that is used as a threshold when generating for additional plans. In each subsequent pass, a set of implementation and transformation rules is used to generate one or more plans whose cost does not exceed the threshold. An optimal plan is selected from the generated plans as the one having the lowest cost.

System and method for optimizing database queries

A system and method for optimizing a database query with improved performance enhancements is herein disclosed. The database query consists of one or more logical expressions. Through the repeated application of one or more rules, the logical expressions are transformed into physical expressions and in some cases, execution plans that implement the database query. Each expression has associated with it a set of group attributes that specifies its characteristic inputs and outputs and a cost that estimates the computational expense for executing the expression. The group attributes are used to categorize similar expressions into groups that are stored in a search data structure. They are also used to track duplicate expressions. The cost associated with an expression is used to guide the search process to consider those expressions that will produce low cost plans. The cost is estimated in accordance with a six-fold criteria with each criterion weighted to account for the context of the expression and the application's particular computing environment. The query optimizer is rule-based including transformation and implementation rules that are used to perform transformations on the logical expressions in a subproblem in order to produce a plan. A OnceGuidance guidance method is used to select a set of rules in certain cases that prevent the regeneration of an existing expression.

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Cupertino, CA, United States of America

Jay Vaishnav