Using historical information to improve search across heterogeneous indices

A system for searching for data, comprising one or more processing units configured for:

• receiving a query and a search scope including a set of specified entities;
• for each of said specified entities, estimating a number of documents that would be identified in a search through said each entity to answer said query;
• on the basis of said estimating, forming a subset of said entities;
• and
• sending said query and said subset of entities to a search engine to search said subset of entities to answer said query.

An article of manufacture comprising:

• at least one computer usable medium having computer readable program code logic to execute instructions in a processing unit for searching for data, said computer readable program code logic, when executing, performing the following:
• receiving a query and a search scope including a set of specified entities;
• for each of said specified entities, estimating a number of documents that would be identified in a search through said each entity to answer said query;
• on the basis of said estimating, forming a subset of said entities;
• and
• sending said query and said subset of entities to a search engine to search said subset of entities to answer said query.

A method of searching for data using heterogeneous indices, comprising:

• searching through a search index, using a first query, to identify a set of entities;
• identifying a second query for searching through said set of entities;
• for each of said set of entities, estimating a number of documents that would be identified in a search through said each entity to answer said second query;
• on the basis of said estimating, forming a subset of said entities;
• and
• sending said second query and said subset of entities to a search engine to search said subset of entities to answer said second query.