arangosh> db._create("test"); 
[ArangoCollection 482014091, "test" (type document, status loaded)]
arangosh> for (i = 0; i < 100; ++i) { db.test.save({ value: i }); }
arangosh> db.test.ensureSkiplist("value");
{ 
  "id" : "test/502002571", 
  "type" : "skiplist", 
  "fields" : [ 
    "value" 
  ], 
  "unique" : false, 
  "sparse" : false, 
  "isNewlyCreated" : true, 
  "code" : 201 
}
arangosh> stmt = db._createStatement("FOR i IN test FILTER i.value > 97 SORT i.value RETURN i.value");
[object ArangoStatement]
arangosh> stmt.explain();
{ 
  "plan" : { 
    "nodes" : [ 
      { 
        "type" : "SingletonNode", 
        "dependencies" : [ ], 
        "id" : 1, 
        "estimatedCost" : 1, 
        "estimatedNrItems" : 1 
      }, 
      { 
        "type" : "IndexRangeNode", 
        "dependencies" : [ 
          1 
        ], 
        "id" : 9, 
        "estimatedCost" : 48, 
        "estimatedNrItems" : 47, 
        "database" : "_system", 
        "collection" : "test", 
        "outVariable" : { 
          "id" : 0, 
          "name" : "i" 
        }, 
        "ranges" : [ 
          [ 
            { 
              "variable" : "i", 
              "attr" : "value", 
              "lowConst" : { 
                "bound" : 97, 
                "include" : false, 
                "isConstant" : true 
              }, 
              "highConst" : { 
                "include" : false, 
                "isConstant" : true 
              }, 
              "lows" : [ ], 
              "highs" : [ ], 
              "valid" : true, 
              "equality" : false 
            } 
          ] 
        ], 
        "index" : { 
          "type" : "skiplist", 
          "id" : "502002571", 
          "unique" : false, 
          "sparse" : false, 
          "fields" : [ 
            "value" 
          ] 
        }, 
        "reverse" : false 
      }, 
      { 
        "type" : "CalculationNode", 
        "dependencies" : [ 
          9 
        ], 
        "id" : 5, 
        "estimatedCost" : 95, 
        "estimatedNrItems" : 47, 
        "expression" : { 
          "type" : "attribute access", 
          "name" : "value", 
          "subNodes" : [ 
            { 
              "type" : "reference", 
              "name" : "i", 
              "id" : 0 
            } 
          ] 
        }, 
        "outVariable" : { 
          "id" : 4, 
          "name" : "3" 
        }, 
        "canThrow" : false, 
        "expressionType" : "attribute" 
      }, 
      { 
        "type" : "ReturnNode", 
        "dependencies" : [ 
          5 
        ], 
        "id" : 8, 
        "estimatedCost" : 142, 
        "estimatedNrItems" : 47, 
        "inVariable" : { 
          "id" : 4, 
          "name" : "3" 
        } 
      } 
    ], 
    "rules" : [ 
      "move-calculations-up", 
      "move-filters-up", 
      "remove-redundant-calculations", 
      "remove-unnecessary-calculations", 
      "move-calculations-up-2", 
      "move-filters-up-2", 
      "use-index-range", 
      "remove-filter-covered-by-index", 
      "use-index-for-sort" 
    ], 
    "collections" : [ 
      { 
        "name" : "test", 
        "type" : "read" 
      } 
    ], 
    "variables" : [ 
      { 
        "id" : 6, 
        "name" : "5" 
      }, 
      { 
        "id" : 4, 
        "name" : "3" 
      }, 
      { 
        "id" : 2, 
        "name" : "1" 
      }, 
      { 
        "id" : 0, 
        "name" : "i" 
      } 
    ], 
    "estimatedCost" : 142, 
    "estimatedNrItems" : 47 
  }, 
  "warnings" : [ ], 
  "stats" : { 
    "rulesExecuted" : 34, 
    "rulesSkipped" : 0, 
    "plansCreated" : 1 
  } 
}