Method selectMetricHeatmap

pkg/metrics/query_handler.go:488–546

(
	ctx context.Context, f *QueryFilter,
)

}

func (h *QueryHandler) selectMetricHeatmap(
	ctx context.Context, f *QueryFilter,
) (*histutil.Heatmap, error) {
	tableName, groupingInterval := DatapointTableForGrouping(
		&f.TimeFilter, org.GroupingIntervalLarge)

	q := h.CH.NewSelect().
		ColumnExpr("quantilesBFloat16MergeState(0.5, 0.9, 0.99)(d.histogram) AS value").
		ColumnExpr("toStartOfInterval(d.time, INTERVAL ? minute) AS time_",
			groupingInterval.Minutes()).
		TableExpr("? AS d", ch.Name(tableName)).
		Where("d.project_id = ?", f.Project.ID).
		Where("d.metric = ?", f.Metric[0]).
		Where("d.time >= ?", f.TimeGTE).
		Where("d.time < ?", f.TimeLT).
		GroupExpr("time_").
		OrderExpr("time_").
		Limit(10000)

	for _, part := range f.allParts {
		if part.Error.Wrapped != nil {
			continue
		}
		switch ast := part.AST.(type) {
		case *ast.Selector:
			part.Error.Wrapped = errors.New("not supported by heatmap")
		case *ast.Grouping:
			part.Error.Wrapped = errors.New("not supported by heatmap")
		case *ast.Where:
			if err := compileFilters(q, InstrumentHistogram, ast.Filters); err != nil {
				part.Error.Wrapped = err
			}
		default:
			return nil, fmt.Errorf("unexpected ast: %T", ast)
		}
	}

	var bfloat16Col []map[bfloat16.T]uint64
	var timeCol []time.Time

	if err := q.ScanColumns(ctx, &bfloat16Col, &timeCol); err != nil {
		return nil, err
	}

	tdigestCol := make([][]float32, len(bfloat16Col))
	for i, m := range bfloat16Col {
		tdigest := make([]float32, 0, 2*len(m))
		for value, count := range m {
			tdigest = append(tdigest, value.Float32(), float32(count))
		}
		tdigestCol[i] = tdigest
	}

	tdigestCol = bunutil.Fill(tdigestCol, timeCol, nil, f.TimeGTE, f.TimeLT, groupingInterval)
	timeCol = bunutil.FillTime(timeCol, f.TimeGTE, f.TimeLT, groupingInterval)
	heatmap := histutil.BuildHeatmap(tdigestCol, timeCol)

	return heatmap, nil