Add $__unixEpochGroup macro to postgres datasource

docs/sources/features/datasources/postgres.md

@@ -68,6 +68,8 @@ Macro example | Description
 *$__unixEpochFilter(dateColumn)* | Will be replaced by a time range filter using the specified column name with times represented as unix timestamp. For example, *dateColumn >= 1494410783 AND dateColumn <= 1494497183*
 *$__unixEpochFrom()* | Will be replaced by the start of the currently active time selection as unix timestamp. For example, *1494410783*
 *$__unixEpochTo()* | Will be replaced by the end of the currently active time selection as unix timestamp. For example, *1494497183*
+*$__unixEpochGroup(dateColumn,'5m', [fillmode])* | Same as $__timeGroup but for times stored as unix timestamp (only available in Grafana 5.3+).
+*$__unixEpochGroupAlias(dateColumn,'5m', [fillmode])* | Same as above but also adds a column alias (only available in Grafana 5.3+).
 
 We plan to add many more macros. If you have suggestions for what macros you would like to see, please [open an issue](https://github.com/grafana/grafana) in our GitHub repo.
 

pkg/tsdb/postgres/macros.go

@@ -134,6 +134,27 @@ func (m *postgresMacroEngine) evaluateMacro(name string, args []string) (string,
 		return fmt.Sprintf("%d", m.timeRange.GetFromAsSecondsEpoch()), nil
 	case "__unixEpochTo":
 		return fmt.Sprintf("%d", m.timeRange.GetToAsSecondsEpoch()), nil
+	case "__unixEpochGroup":
+		if len(args) < 2 {
+			return "", fmt.Errorf("macro %v needs time column and interval and optional fill value", name)
+		}
+		interval, err := time.ParseDuration(strings.Trim(args[1], `'`))
+		if err != nil {
+			return "", fmt.Errorf("error parsing interval %v", args[1])
+		}
+		if len(args) == 3 {
+			err := tsdb.SetupFillmode(m.query, interval, args[2])
+			if err != nil {
+				return "", err
+			}
+		}
+		return fmt.Sprintf("floor(%s/%v)*%v", args[0], interval.Seconds(), interval.Seconds()), nil
+	case "__unixEpochGroupAlias":
+		tg, err := m.evaluateMacro("__unixEpochGroup", args)
+		if err == nil {
+			return tg + " AS \"time\"", err
+		}
+		return "", err
 	default:
 		return "", fmt.Errorf("Unknown macro %v", name)
 	}

pkg/tsdb/postgres/macros_test.go

@@ -110,6 +110,18 @@ func TestMacroEngine(t *testing.T) {
 
 				So(sql, ShouldEqual, fmt.Sprintf("select %d", to.Unix()))
 			})
+
+			Convey("interpolate __unixEpochGroup function", func() {
+
+				sql, err := engine.Interpolate(query, timeRange, "SELECT $__unixEpochGroup(time_column,'5m')")
+				So(err, ShouldBeNil)
+				sql2, err := engine.Interpolate(query, timeRange, "SELECT $__unixEpochGroupAlias(time_column,'5m')")
+				So(err, ShouldBeNil)
+
+				So(sql, ShouldEqual, "SELECT floor(time_column/300)*300")
+				So(sql2, ShouldEqual, sql+" AS \"time\"")
+			})
+
 		})
 
 		Convey("Given a time range between 1960-02-01 07:00 and 1965-02-03 08:00", func() {

public/app/plugins/datasource/postgres/partials/query.editor.html

@@ -57,6 +57,8 @@ Macros:
      by setting fillvalue grafana will fill in missing values according to the interval
      fillvalue can be either a literal value, NULL or previous; previous will fill in the previous seen value or NULL if none has been seen yet
 - $__timeGroupAlias(column,'5m') -> (extract(epoch from column)/300)::bigint*300 AS "time"
+- $__unixEpochGroup(column,'5m') -> floor(column/300)*300
+- $__unixEpochGroupAlias(column,'5m') -> floor(column/300)*300 AS "time"
 
 Example of group by and order by with $__timeGroup:
 SELECT