feat: add limit to SelectSeries API

api/openapiv2/gen/phlare.swagger.json

@@ -2179,6 +2179,10 @@
           "items": {
             "type": "string"
           }
+        },
+        "limit": {
+          "type": "string",
+          "format": "int64"
         }
       }
     },

api/querier/v1/querier.proto

@@ -162,6 +162,8 @@ message SelectSeriesRequest {
   optional types.v1.TimeSeriesAggregationType aggregation = 7;
   // Select stack traces that match the provided selector.
   optional types.v1.StackTraceSelector stack_trace_selector = 8;
+  // Select the top N series by total value.
+  optional int64 limit = 9;
 }
 
 message SelectSeriesResponse {

api/query/v1/query.proto

@@ -156,6 +156,7 @@ message SeriesLabelsReport {
 message TimeSeriesQuery {
   double step = 1;
   repeated string group_by = 2;
+  int64 limit = 3;
 }
 
 message TimeSeriesReport {

pkg/frontend/frontend_select_time_series.go

@@ -84,5 +84,6 @@ func (f *Frontend) SelectSeries(
 		return nil, err
 	}
 
-	return connect.NewResponse(&querierv1.SelectSeriesResponse{Series: m.TimeSeries()}), nil
+	series := m.Top(int(c.Msg.GetLimit()))
+	return connect.NewResponse(&querierv1.SelectSeriesResponse{Series: series}), nil
 }

pkg/frontend/read_path/query_frontend/query_select_time_series.go

@@ -10,6 +10,7 @@ import (
 
 	querierv1 "github.com/grafana/pyroscope/api/gen/proto/go/querier/v1"
 	queryv1 "github.com/grafana/pyroscope/api/gen/proto/go/query/v1"
+	phlaremodel "github.com/grafana/pyroscope/pkg/model"
 	"github.com/grafana/pyroscope/pkg/validation"
 )
 
@@ -50,6 +51,7 @@ func (q *QueryFrontend) SelectSeries(
 			TimeSeries: &queryv1.TimeSeriesQuery{
 				Step:    c.Msg.GetStep(),
 				GroupBy: c.Msg.GetGroupBy(),
+				Limit:   c.Msg.GetLimit(),
 			},
 		}},
 	})
@@ -59,5 +61,6 @@ func (q *QueryFrontend) SelectSeries(
 	if report == nil {
 		return connect.NewResponse(&querierv1.SelectSeriesResponse{}), nil
 	}
-	return connect.NewResponse(&querierv1.SelectSeriesResponse{Series: report.TimeSeries.TimeSeries}), nil
+	series := phlaremodel.TopSeries(report.TimeSeries.TimeSeries, int(c.Msg.GetLimit()))
+	return connect.NewResponse(&querierv1.SelectSeriesResponse{Series: series}), nil
 }