querier: Actually use select mint,maxt params during select.

This will definitely helps with offset queries.

Same was done on cortexproject/cortex#1012

Signed-off-by: Bartek Plotka <bwplotka@gmail.com>

Author: bwplotka

pkg/query/api/v1.go

@@ -503,19 +503,20 @@ func (api *API) series(r *http.Request) (interface{}, []error, *ApiError) {
 	}
 
 	// TODO(bwplotka): Support downsampling?
-	q, err := api.queryableCreate(enableDedup, replicaLabels, 0, enablePartialResponse).Querier(r.Context(), timestamp.FromTime(start), timestamp.FromTime(end))
+	q, err := api.queryableCreate(enableDedup, replicaLabels, 0, enablePartialResponse).
+		Querier(r.Context(), timestamp.FromTime(start), timestamp.FromTime(end))
 	if err != nil {
 		return nil, nil, &ApiError{errorExec, err}
 	}
 	defer runutil.CloseWithLogOnErr(api.logger, q, "queryable series")
 
 	var (
 		warnings []error
-		metrics  = []labels.Labels{}
+		metrics  []labels.Labels
 		sets     []storage.SeriesSet
 	)
 	for _, mset := range matcherSets {
-		s, warns, err := q.Select(&storage.SelectParams{}, mset...)
+		s, warns, err := q.Select(nil, mset...)
 		if err != nil {
 			return nil, nil, &ApiError{errorExec, err}
 		}

pkg/query/querier.go

@@ -169,12 +169,18 @@ func (q *querier) Select(params *storage.SelectParams, ms ...*labels.Matcher) (s
 		return nil, nil, errors.Wrap(err, "convert matchers")
 	}
 
+	if params == nil {
+		params = &storage.SelectParams{
+			Start: q.mint,
+			End:   q.maxt,
+		}
+	}
 	queryAggrs, resAggr := aggrsFromFunc(params.Func)
 
 	resp := &seriesServer{ctx: ctx}
 	if err := q.proxy.Series(&storepb.SeriesRequest{
-		MinTime:                 q.mint,
-		MaxTime:                 q.maxt,
+		MinTime:                 params.Start,
+		MaxTime:                 params.End,
 		Matchers:                sms,
 		MaxResolutionWindow:     q.maxResolutionMillis,
 		Aggregates:              queryAggrs,