// 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
}
// createTagSetGroupIterators creates a set of iterators for a subset of a tagset's series.
func (e *Engine) createTagSetGroupIterators(ref *influxql.VarRef, mm *tsdb.Measurement, seriesKeys []string, t *influxql.TagSet, filters []influxql.Expr, opt influxql.IteratorOptions) ([]influxql.Iterator, error) {
conditionFields := make([]influxql.VarRef, len(influxql.ExprNames(opt.Condition)))
itrs := make([]influxql.Iterator, 0, len(seriesKeys))
for i, seriesKey := range seriesKeys {
fields := 0
if filters[i] != nil {
// Retrieve non-time fields from this series filter and filter out tags.
for _, f := range influxql.ExprNames(filters[i]) {
conditionFields[fields] = f
fields++
}
}
itr, err := e.createVarRefSeriesIterator(ref, mm, seriesKey, t, filters[i], conditionFields[:fields], opt)
if err != nil {
return itrs, err
} else if itr == nil {
continue
}
itrs = append(itrs, itr)
}
return itrs, nil
}