Allow percentile to be used as a selector

Fixes #6292.

CHANGELOG.md

@@ -5,6 +5,7 @@
 - [#6237](https://github.com/influxdata/influxdb/issues/6237): Enable continuous integration testing on Windows platform via AppVeyor. Thanks @mvadu
 - [#6263](https://github.com/influxdata/influxdb/pull/6263): Reduce UDP Service allocation size.
 - [#6228](https://github.com/influxdata/influxdb/pull/6228): Support for multiple listeners for collectd and OpenTSDB inputs.
+- [#6292](https://github.com/influxdata/influxdb/issues/6292): Allow percentile to be used as a selector.
 
 ### Bugfixes
 

cmd/influxd/run/server_test.go

@@ -3564,13 +3564,13 @@ func TestServer_Query_AggregateSelectors(t *testing.T) {
 			name:    "percentile - time",
 			params:  url.Values{"db": []string{"db0"}},
 			command: `SELECT time, percentile(rx, 75) FROM network where time >= '2000-01-01T00:00:00Z' AND time <= '2000-01-01T00:01:29Z' group by time(30s)`,
-			exp:     `{"error":"error parsing query: mixing aggregate and non-aggregate queries is not supported"}`,
+			exp:     `{"results":[{"series":[{"name":"network","columns":["time","percentile"],"values":[["2000-01-01T00:00:00Z",40],["2000-01-01T00:00:30Z",50],["2000-01-01T00:01:00Z",70]]}]}]}`,
 		},
 		&Query{
 			name:    "percentile - tx",
 			params:  url.Values{"db": []string{"db0"}},
 			command: `SELECT tx, percentile(rx, 75) FROM network where time >= '2000-01-01T00:00:00Z' AND time <= '2000-01-01T00:01:29Z' group by time(30s)`,
-			exp:     `{"error":"error parsing query: mixing aggregate and non-aggregate queries is not supported"}`,
+			exp:     `{"results":[{"series":[{"name":"network","columns":["time","tx","percentile"],"values":[["2000-01-01T00:00:00Z",50,40],["2000-01-01T00:00:30Z",70,50],["2000-01-01T00:01:00Z",30,70]]}]}]}`,
 		},
 	}...)
 

influxql/ast.go

@@ -1403,12 +1403,12 @@ func (s *SelectStatement) validSelectWithAggregate() error {
 			numAggregates++
 		}
 	}
-	// For TOP, BOTTOM, MAX, MIN, FIRST, LAST (selector functions) it is ok to ask for fields and tags
+	// For TOP, BOTTOM, MAX, MIN, FIRST, LAST, PERCENTILE (selector functions) it is ok to ask for fields and tags
 	// but only if one function is specified.  Combining multiple functions and fields and tags is not currently supported
 	onlySelectors := true
 	for k := range calls {
 		switch k {
-		case "top", "bottom", "max", "min", "first", "last":
+		case "top", "bottom", "max", "min", "first", "last", "percentile":
 		default:
 			onlySelectors = false
 			break

influxql/call_iterator.go

@@ -920,7 +920,7 @@ func NewFloatPercentileReduceSliceFunc(percentile float64) FloatReduceSliceFunc
 		}
 
 		sort.Sort(floatPointsByValue(a))
-		return []FloatPoint{{Time: ZeroTime, Value: a[i].Value, Aux: a[i].Aux}}
+		return []FloatPoint{{Time: a[i].Time, Value: a[i].Value, Aux: a[i].Aux}}
 	}
 }
 

influxql/parser_test.go

@@ -382,6 +382,18 @@ func TestParser_ParseStatement(t *testing.T) {
 			},
 		},
 
+		{
+			s: `select percentile("field1", 2.0), field2 from cpu`,
+			stmt: &influxql.SelectStatement{
+				IsRawQuery: false,
+				Fields: []*influxql.Field{
+					{Expr: &influxql.Call{Name: "percentile", Args: []influxql.Expr{&influxql.VarRef{Val: "field1"}, &influxql.NumberLiteral{Val: 2.0}}}},
+					{Expr: &influxql.VarRef{Val: "field2"}},
+				},
+				Sources: []influxql.Source{&influxql.Measurement{Name: "cpu"}},
+			},
+		},
+
 		// select top statements
 		{
 			s: `select top("field1", 2) from cpu`,