shell> curl -X POST --data-binary @- --dump - http://localhost:8529/_api/explain
{"query":"FOR p IN products LET a = p.id FILTER a == 4 LET name = p.name SORT p.id LIMIT 1 RETURN name"}

HTTP/1.1 200 OK
content-type: application/json; charset=utf-8

{ 
  "plan" : { 
    "nodes" : [ 
      { 
        "type" : "SingletonNode", 
        "dependencies" : [ ], 
        "id" : 1, 
        "estimatedCost" : 1, 
        "estimatedNrItems" : 1 
      }, 
      { 
        "type" : "IndexRangeNode", 
        "dependencies" : [ 
          1 
        ], 
        "id" : 11, 
        "estimatedCost" : 11, 
        "estimatedNrItems" : 10, 
        "database" : "_system", 
        "collection" : "products", 
        "outVariable" : { 
          "id" : 0, 
          "name" : "p" 
        }, 
        "ranges" : [ 
          [ ] 
        ], 
        "index" : { 
          "type" : "skiplist", 
          "id" : "1163585143", 
          "unique" : false, 
          "sparse" : false, 
          "fields" : [ 
            "id" 
          ] 
        }, 
        "reverse" : false 
      }, 
      { 
        "type" : "CalculationNode", 
        "dependencies" : [ 
          11 
        ], 
        "id" : 3, 
        "estimatedCost" : 21, 
        "estimatedNrItems" : 10, 
        "expression" : { 
          "type" : "attribute access", 
          "name" : "id", 
          "subNodes" : [ 
            { 
              "type" : "reference", 
              "name" : "p", 
              "id" : 0 
            } 
          ] 
        }, 
        "outVariable" : { 
          "id" : 1, 
          "name" : "a" 
        }, 
        "canThrow" : false 
      }, 
      { 
        "type" : "CalculationNode", 
        "dependencies" : [ 
          3 
        ], 
        "id" : 4, 
        "estimatedCost" : 31, 
        "estimatedNrItems" : 10, 
        "expression" : { 
          "type" : "compare ==", 
          "subNodes" : [ 
            { 
              "type" : "reference", 
              "name" : "a", 
              "id" : 1 
            }, 
            { 
              "type" : "value", 
              "value" : 4 
            } 
          ] 
        }, 
        "outVariable" : { 
          "id" : 3, 
          "name" : "3" 
        }, 
        "canThrow" : false 
      }, 
      { 
        "type" : "FilterNode", 
        "dependencies" : [ 
          4 
        ], 
        "id" : 5, 
        "estimatedCost" : 41, 
        "estimatedNrItems" : 10, 
        "inVariable" : { 
          "id" : 3, 
          "name" : "3" 
        } 
      }, 
      { 
        "type" : "LimitNode", 
        "dependencies" : [ 
          5 
        ], 
        "id" : 9, 
        "estimatedCost" : 42, 
        "estimatedNrItems" : 1, 
        "offset" : 0, 
        "limit" : 1, 
        "fullCount" : false 
      }, 
      { 
        "type" : "CalculationNode", 
        "dependencies" : [ 
          9 
        ], 
        "id" : 6, 
        "estimatedCost" : 43, 
        "estimatedNrItems" : 1, 
        "expression" : { 
          "type" : "attribute access", 
          "name" : "name", 
          "subNodes" : [ 
            { 
              "type" : "reference", 
              "name" : "p", 
              "id" : 0 
            } 
          ] 
        }, 
        "outVariable" : { 
          "id" : 2, 
          "name" : "name" 
        }, 
        "canThrow" : false 
      }, 
      { 
        "type" : "ReturnNode", 
        "dependencies" : [ 
          6 
        ], 
        "id" : 10, 
        "estimatedCost" : 44, 
        "estimatedNrItems" : 1, 
        "inVariable" : { 
          "id" : 2, 
          "name" : "name" 
        } 
      } 
    ], 
    "rules" : [ 
      "move-calculations-up", 
      "remove-redundant-calculations", 
      "move-calculations-up-2", 
      "use-index-for-sort", 
      "remove-unnecessary-calculations-2", 
      "move-calculations-down" 
    ], 
    "collections" : [ 
      { 
        "name" : "products", 
        "type" : "read" 
      } 
    ], 
    "variables" : [ 
      { 
        "id" : 4, 
        "name" : "4" 
      }, 
      { 
        "id" : 3, 
        "name" : "3" 
      }, 
      { 
        "id" : 2, 
        "name" : "name" 
      }, 
      { 
        "id" : 1, 
        "name" : "a" 
      }, 
      { 
        "id" : 0, 
        "name" : "p" 
      } 
    ], 
    "estimatedCost" : 44, 
    "estimatedNrItems" : 1 
  }, 
  "warnings" : [ ], 
  "stats" : { 
    "rulesExecuted" : 32, 
    "rulesSkipped" : 0, 
    "plansCreated" : 1 
  }, 
  "error" : false, 
  "code" : 200 
}