Golang influxql.LimitTagSets函數代碼示例

func (e *Engine) SeriesKeys(opt influxql.IteratorOptions) (influxql.SeriesList, error) {
	seriesList := influxql.SeriesList{}
	mms := tsdb.Measurements(e.index.MeasurementsByName(influxql.Sources(opt.Sources).Names()))
	for _, mm := range mms {
		// Determine tagsets for this measurement based on dimensions and filters.
		tagSets, err := mm.TagSets(opt.Dimensions, opt.Condition)
		if err != nil {
			return nil, err
		}

		// Calculate tag sets and apply SLIMIT/SOFFSET.
		tagSets = influxql.LimitTagSets(tagSets, opt.SLimit, opt.SOffset)
		for _, t := range tagSets {
			series := influxql.Series{
				Name: mm.Name,
				Tags: influxql.NewTags(t.Tags),
				Aux:  make([]influxql.DataType, len(opt.Aux)),
			}

			// Determine the aux field types.
			for _, seriesKey := range t.SeriesKeys {
				tags := influxql.NewTags(e.index.TagsForSeries(seriesKey))
				for i, field := range opt.Aux {
					typ := func() influxql.DataType {
						mf := e.measurementFields[mm.Name]
						if mf == nil {
							return influxql.Unknown
						}

						f := mf.Field(field)
						if f == nil {
							return influxql.Unknown
						}
						return f.Type
					}()

					if typ == influxql.Unknown {
						if v := tags.Value(field); v != "" {
							// All tags are strings.
							typ = influxql.String
						}
					}

					if typ != influxql.Unknown {
						if series.Aux[i] == influxql.Unknown || typ < series.Aux[i] {
							series.Aux[i] = typ
						}
					}
				}
			}
			seriesList = append(seriesList, series)
		}
	}
	return seriesList, nil
}

// createVarRefIterator creates an iterator for a variable reference.
func (e *Engine) createVarRefIterator(opt influxql.IteratorOptions) ([]influxql.Iterator, error) {
	ref, _ := opt.Expr.(*influxql.VarRef)

	var itrs []influxql.Iterator
	if err := func() error {
		mms := tsdb.Measurements(e.index.MeasurementsByName(influxql.Sources(opt.Sources).Names()))

		// Retrieve the maximum number of fields (without time).
		conditionFields := make([]string, len(influxql.ExprNames(opt.Condition)))

		for _, mm := range mms {
			// Determine tagsets for this measurement based on dimensions and filters.
			tagSets, err := mm.TagSets(opt.Dimensions, opt.Condition)
			if err != nil {
				return err
			}

			// Calculate tag sets and apply SLIMIT/SOFFSET.
			tagSets = influxql.LimitTagSets(tagSets, opt.SLimit, opt.SOffset)

			for _, t := range tagSets {
				for i, seriesKey := range t.SeriesKeys {
					fields := 0
					if t.Filters[i] != nil {
						// Retrieve non-time fields from this series filter and filter out tags.
						for _, f := range influxql.ExprNames(t.Filters[i]) {
							if mm.HasField(f) {
								conditionFields[fields] = f
								fields++
							}
						}
					}

					itr, err := e.createVarRefSeriesIterator(ref, mm, seriesKey, t, t.Filters[i], conditionFields[:fields], opt)
					if err != nil {
						return err
					} else if itr == nil {
						continue
					}
					itrs = append(itrs, itr)
				}
			}
		}
		return nil
	}(); err != nil {
		influxql.Iterators(itrs).Close()
		return nil, err
	}

	return itrs, nil
}

// createVarRefIterator creates an iterator for a variable reference.
func (e *Engine) createVarRefIterator(opt influxql.IteratorOptions) ([]influxql.Iterator, error) {
	ref, _ := opt.Expr.(*influxql.VarRef)

	var itrs []influxql.Iterator
	if err := func() error {
		mms := tsdb.Measurements(e.index.MeasurementsByName(influxql.Sources(opt.Sources).Names()))

		for _, mm := range mms {
			// Determine tagsets for this measurement based on dimensions and filters.
			tagSets, err := mm.TagSets(opt.Dimensions, opt.Condition)
			if err != nil {
				return err
			}

			// Calculate tag sets and apply SLIMIT/SOFFSET.
			tagSets = influxql.LimitTagSets(tagSets, opt.SLimit, opt.SOffset)

			for _, t := range tagSets {
				inputs, err := e.createTagSetIterators(ref, mm, t, opt)
				if err != nil {
					return err
				}

				if len(inputs) > 0 && (opt.Limit > 0 || opt.Offset > 0) {
					var itr influxql.Iterator
					if opt.MergeSorted() {
						itr = influxql.NewSortedMergeIterator(inputs, opt)
					} else {
						itr = influxql.NewMergeIterator(inputs, opt)
					}
					itrs = append(itrs, newLimitIterator(itr, opt))
				} else {
					itrs = append(itrs, inputs...)
				}
			}
		}
		return nil
	}(); err != nil {
		influxql.Iterators(itrs).Close()
		return nil, err
	}

	return itrs, nil
}