Documentation

SortMode prescribes how to handle sorting array/multi-valued fields.

http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-sort.html#_sort_mode_option

mkSort defaults everything but the FieldName and the SortOrder so that you can concisely describe the usual kind of SortSpecs you want.

Sort is a synonym for a list of SortSpecs. Sort behavior is order dependent with later sorts acting as tie-breakers for earlier sorts.

The two main kinds of SortSpec are DefaultSortSpec and GeoDistanceSortSpec. The latter takes a SortOrder, GeoPoint, and DistanceUnit to express "nearness" to a single geographical point as a sort specification.

http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-sort.html#search-request-sort

DefaultSort is usually the kind of SortSpec you'll want. There's a mkSort convenience function for when you want to specify only the most common parameters.

The ignoreUnmapped, when Just field is used to set the elastic unmapped_type

http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-sort.html#search-request-sort

SortOrder is Ascending or Descending, as you might expect. These get encoded into "asc" or "desc" when turned into JSON.

http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-sort.html#search-request-sort

Missing prescribes how to handle missing fields. A missing field can be sorted last, first, or using a custom value as a substitute.

http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-sort.html#_missing_values