Merge branch 'dahankzter-master'

CHANGELOG.md

@@ -8,6 +8,7 @@
 ### Bugfixes
 
 - [3013](https://github.com/influxdb/influxdb/issues/3013): Panic error with inserting values with commas
+- [#2956](https://github.com/influxdb/influxdb/issues/2956): Type mismatch in derivative
 - [#2908](https://github.com/influxdb/influxdb/issues/2908): Field mismatch error messages need to be updated
 - [#2931](https://github.com/influxdb/influxdb/pull/2931): Services and reporting should wait until cluster has leader.
 - [#2943](https://github.com/influxdb/influxdb/issues/2943): Ensure default retention policies are fully replicated

influxql/engine.go

@@ -3,6 +3,7 @@ package influxql
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"hash/fnv"
 	"math"
 	"sort"
@@ -408,7 +409,8 @@ func (m *MapReduceJob) processRawQueryDerivative(lastValueFromPreviousChunk *raw
 
 		// Calculate the derivative of successive points by dividing the difference
 		// of each value by the elapsed time normalized to the interval
-		diff := v.Values.(float64) - lastValueFromPreviousChunk.Values.(float64)
+		diff := i64tof64(v.Values) - i64tof64(lastValueFromPreviousChunk.Values)
+
 		elapsed := v.Time - lastValueFromPreviousChunk.Time
 
 		value := 0.0
@@ -468,7 +470,7 @@ func (m *MapReduceJob) processDerivative(results [][]interface{}) [][]interface{
 		}
 
 		elapsed := cur[0].(time.Time).Sub(prev[0].(time.Time))
-		diff := cur[1].(float64) - prev[1].(float64)
+		diff := i64tof64(cur[1]) - i64tof64(prev[1])
 		value := 0.0
 		if elapsed > 0 {
 			value = float64(diff) / (float64(elapsed) / float64(m.derivativeInterval()))
@@ -930,6 +932,16 @@ func (e *Executor) execute(out chan *Row) {
 	close(out)
 }
 
+func i64tof64(v interface{}) float64 {
+	switch v.(type) {
+	case int64:
+		return float64(v.(int64))
+	case float64:
+		return v.(float64)
+	}
+	panic(fmt.Sprintf("expected either int64 or float64, got %v", v))
+}
+
 // Row represents a single row returned from the execution of a statement.
 type Row struct {
 	Name    string            `json:"name,omitempty"`

influxql/engine_test.go

@@ -206,6 +206,36 @@ func TestProcessDerivative(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:     "float derivatives",
+			fn:       "derivative",
+			interval: "1d",
+			in: [][]interface{}{
+				[]interface{}{
+					time.Unix(0, 0), 1.0,
+				},
+				[]interface{}{
+					time.Unix(0, 0).Add(24 * time.Hour), int64(3),
+				},
+				[]interface{}{
+					time.Unix(0, 0).Add(48 * time.Hour), int64(5),
+				},
+				[]interface{}{
+					time.Unix(0, 0).Add(72 * time.Hour), int64(9),
+				},
+			},
+			exp: [][]interface{}{
+				[]interface{}{
+					time.Unix(0, 0).Add(24 * time.Hour), 2.0,
+				},
+				[]interface{}{
+					time.Unix(0, 0).Add(48 * time.Hour), 2.0,
+				},
+				[]interface{}{
+					time.Unix(0, 0).Add(72 * time.Hour), 4.0,
+				},
+			},
+		},
 	}
 
 	for _, test := range tests {