The search_after parameter provides a way to efficiently paginate from one page to the next. This parameter accepts an array of sort values, those values are then used by the searcher to sort the top hits from the first document that is greater to the sort values.
This parameter must be used in conjunction with the sort parameter, it must contain exactly the same number of values than the number of fields to sort on.
NOTE: A field with one unique value per document should be used as the last element of the sort specification. Otherwise the sort order for documents that have the same sort values would be undefined. The recommended way is to use the field `_uuid` which is certain to contain one unique value for each document.
Fixes#8192
Nik Everett
Jim Ferenczi