14. A computer program product comprising computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising computer readable instructions configured to perform a method comprising: receiving a search query from a user; receiving, from a search engine, a set of search results that satisfy the search query; identifying a user interest profile associated with the user, the user interest profile comprising a set of standalone user interest vectors combined into an overall interest vector, wherein each of the set of standalone user interest vectors comprises a set of information associated with one or more activities performed by the user with respect to a corresponding social system, wherein each of the set of standalone user interest vectors is assigned a source weight based on a corresponding social system, wherein the source weight is adjustable based on a performance of the standalone interest vector with respect to personalizing the set of search results; assigning a ranking score, based at least on the user interest profile, to each result in at least a subset of search results in the set of search results; sorting the subset of search results based on the ranking score that has assigned to each result in the subset of search results; sending the subset of search results that has been sorted to the user; receiving a set of feedback information from the user associated with the subset of search results that have been sent to the user; and updating the source weight associated with at least one of the set of standalone interest vectors based on the set of feedback that has been received.
14. A computer program product comprising computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising computer readable instructions configured to perform a method comprising: receiving a search query from a user; receiving, from a search engine, a set of search results that satisfy the search query; identifying a user interest profile associated with the user, the user interest profile comprising a set of standalone user interest vectors combined into an overall interest vector, wherein each of the set of standalone user interest vectors comprises a set of information associated with one or more activities performed by the user with respect to a corresponding social system, wherein each of the set of standalone user interest vectors is assigned a source weight based on a corresponding social system, wherein the source weight is adjustable based on a performance of the standalone interest vector with respect to personalizing the set of search results; assigning a ranking score, based at least on the user interest profile, to each result in at least a subset of search results in the set of search results; sorting the subset of search results based on the ranking score that has assigned to each result in the subset of search results; sending the subset of search results that has been sorted to the user; receiving a set of feedback information from the user associated with the subset of search results that have been sent to the user; and updating the source weight associated with at least one of the set of standalone interest vectors based on the set of feedback that has been received. 16. The computer program product of claim 14 , wherein assigning a ranking score further comprises: assigning a final score to each result in the subset of search results by combining an interest-similarity score and a relevancy score associated with the each result, the relevancy score indicating a degree of relevancy between the each result and the search query, wherein combining the interest-similarity score and the relevance score is weighted by a personalization degree in the user interest profile.