Method ReduceResolution

model/histogram/histogram.go:627–654

ReduceResolution reduces the histogram's spans, buckets into target schema. An error is returned in the following cases: - The target schema is not smaller than the current histogram's schema. - The histogram has custom buckets. - The target schema is a custom buckets schema. - Any spans have an inv

(targetSchema int32)

//   - Any spans have an invalid offset.
//   - The spans are inconsistent with the number of buckets.
func (h *Histogram) ReduceResolution(targetSchema int32) error {
	// Note that the follow three returns are not returning a
	// histogram.Error because they are programming errors.
	if h.UsesCustomBuckets() {
		return errors.New("cannot reduce resolution when there are custom buckets")
	}
	if IsCustomBucketsSchema(targetSchema) {
		return errors.New("cannot reduce resolution to custom buckets schema")
	}
	if targetSchema >= h.Schema {
		return fmt.Errorf("cannot reduce resolution from schema %d to %d", h.Schema, targetSchema)
	}

	var err error

	if h.PositiveSpans, h.PositiveBuckets, err = reduceResolution(
		h.PositiveSpans, h.PositiveBuckets, h.Schema, targetSchema, true, true,
	); err != nil {
		return err
	}
	if h.NegativeSpans, h.NegativeBuckets, err = reduceResolution(
		h.NegativeSpans, h.NegativeBuckets, h.Schema, targetSchema, true, true,
	); err != nil {
		return err
	}
	h.Schema = targetSchema
	return nil
}