Ferret

Sorting Search Results

By default, documents are sorted by relevance and then by document ID if scores are equal. But what if we want to sort the result set by the value in one of the fields (e.g., price)? One way to do this is to retrieve the entire result set and make use of Ruby’s Array#sort method. However, this would take too long for large result sets, not to mention use up a lot of unnecessary memory. Searcher provides a :sort parameter for easy sorting. The easiest way to specify a sort is to pass a sort string. A sort string is a comma-separated list of field names with an optional DESC modifier to reverse the sort for that field. The type of the field is automatically detected and the field sorted accordingly. So Float fields will be sorted by Float value, and Integer fields will be sorted by Integer value. SCORE and DOC_ID can be used in place of field names to sort by relevance and internal document ID, respectively. Here are some examples:

index.search(query, :sort => "title, year DESC")
index.search(query, :sort => "SCORE DESC, DOC_ID DESC")
index.search(query, :sort => "SCORE, rating DESC")

Although this will do the job most of the time, you can be a little more explicit in describing how a result set is sorted by using the Sort API. You will also need to use the Sort API to take full advantage of sort caching. There are two classes in the Sort API: Sort and SortField.

Sort Caching Explained

As with filters, sorts are cached when they are run. That is to say, when you ...