Search Planner
Search Planner
The outcome of a CQL query is a set of documents that satisfy the criteria defined by the query. Documents are hosted in a gCube infrastructure by Data Sources. Data Sources are able to execute CQL queries, bound to the information they host, and each Data Source supports different CQL capabilities. In most cases the initial CQL query can not be answered solely by a single Data Source. Therefore we need to use the functionality of Search Operators and combine the sets of documents retrieved from various Data Sources. The Search Planner detects which are the Data Sources that must be involved in order to answer the initial query and produces a plan. This plan specifies a)the subquery of the initial query that must be answered by each Data Source and b)how the Data Sources are combined with Search Operators in order to produce the final outcome.
Search Planner takes into account the following facts about the gCube environment:
- Vertical and Horizontal partitioning of data
- Data Sources CQL capabilities
- The costs implied by the execution of a search plan
