Abstract: An optimizer apparatus and method for application in a query engine of a database management system is provided for optimizing a query expression. One or more blocks are identified in the initial query expression, each of the one or more blocks being identified based on a predetermined sub-expression of the initial query expression. The optimization process is partitioned into one or more sub-tasks, wherein each sub-task corresponds to a respective block. An optimal query plan for each of the sub-tasks is determined.

Abstract: A robust knowledge-based management and sharing system organized by context for expertise-based or context-based searching and retrieval of relevant information is disclosed. The various embodiments and techniques described herein are used to organize a user's data and communications around the user's expertise or one or more contexts the user is associated with such as the user's projects, products, and customers. The organization of user data is derived from the user's competencies and interactions with others and is used to build and index user profiles in a manner that facilitates retrieval in search results for relevant search criteria. A linguistic processing pipeline is used to parse and index the user's data to generate the complete and partial profiles organized by context. Complete and partial profiles are generated, indexed, ranked, and stored by the system.