1. A computer-implemented method comprising: receiving, by a computer device, at least one term to be used in selecting content from a repository for publication; evaluating a record using the at least one term producing a result, the record including one or more query terms and corresponding values for numbers of documents in the repository that are responsive to a given query term, the result comprising a corresponding value for a first query; comparing, by the computer device, the corresponding value for the first query with at least one of a predetermined upper limit or a predetermined lower limit; determining, by the computer device and based on the comparison, a second query to be performed on the repository for selecting at least one of the content items, wherein determining the second query comprises one of: (i) when the corresponding value is greater than the predetermined upper limit, narrowing the first query to obtain the second query including identifying one or more additional terms to join with the at least one term including identifying one or more additional terms based on terms included in a document of the one or more documents that include the at least one term and wherein narrowing further includes creating the second query as a combination of the at least one term and the one or more additional terms; or (ii) when the corresponding value is less than the predetermined lower limit, broadening the first query to obtain the second query including identifying one or more additional terms to join with the at least one term including identifying one or more additional terms based on terms included in a document of the one or more documents that include the at least one term and wherein broadening further includes creating the second query as a combination of the at least one term or the one or more additional terms; and providing, by the computer device and responsive to the at least one term, selected content items that result from performing the second query.