Filter on latest document of each group in Elasticsearch

You can do this with bucket selector aggregation(Only ES 2.x). I am basically comparing max date of each student with max date when they got F grade(filtering) and only retaining results where both dates are same. You can remove top hits aggregation if you want, it is just there to get that particular record where student failed.

{  "size": 0,  "aggs": {    "group_by_students": {      "terms": {        "field": "student"      },      "aggs": {        "only_f_grade_bucket": {          "filter": {            "term": {              "grade": "F"            }          },          "aggs": {            "latest_date": {              "max": {                "field": "date"              }            },            "top_hit":{              "top_hits": {                "size": 1              }            }          }        },        "max_date": {          "max": {            "field": "date"          }        },        "latest_failure": {          "bucket_selector": {            "buckets_path": {              "failed_date": "only_f_grade_bucket.latest_date",              "max_date": "max_date"            },            "script": "failed_date == max_date"          }        }      }    }  }}