Result grouping is a useful feature in Solr; it returns an optimal mix of search results for a query. Result grouping can be performed based on field values, functions, or queries.
Sometimes, we have multiple similar documents for a single search term, for example, multiple locations for the same hospital, recipes for specific food, plans for term insurance, and so on. In the normal way, if we are searching for one such term, it will return all similar documents and we will have to display all of them on the same page. Through result grouping, we can display only a single document (or the top few or some limited number) for each unique value, and provide a message link with meaningful text and the number of total results found for that query. Clicking on that link will expand the full search result list. This is similar to the expand and collapse features of a search application. Result grouping is just as capable as expand and collapse; additionally it removes duplicate documents...