// 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
}
// CreateIterator returns a single combined iterator for the shards.
func (a Shards) CreateIterator(opt influxql.IteratorOptions) (influxql.Iterator, error) {
if influxql.Sources(opt.Sources).HasSystemSource() {
return a.createSystemIterator(opt)
}
// Create iterators for each shard.
// Ensure that they are closed if an error occurs.
itrs := make([]influxql.Iterator, 0, len(a))
if err := func() error {
for _, sh := range a {
itr, err := sh.CreateIterator(opt)
if err != nil {
return err
}
itrs = append(itrs, itr)
}
return nil
}(); err != nil {
influxql.Iterators(itrs).Close()
return nil, err
}
// Merge into a single iterator.
if opt.MergeSorted() {
return influxql.NewSortedMergeIterator(itrs, opt), nil
}
itr := influxql.NewMergeIterator(itrs, opt)
if opt.Expr != nil {
if expr, ok := opt.Expr.(*influxql.Call); ok && expr.Name == "count" {
opt.Expr = &influxql.Call{
Name: "sum",
Args: expr.Args,
}
}
}
return influxql.NewCallIterator(itr, opt), nil
}
func TestIteratorOptions_MergeSorted(t *testing.T) {
opt := influxql.IteratorOptions{}
sorted := opt.MergeSorted()
if !sorted {
t.Error("expected no expression to be sorted, got unsorted")
}
opt.Expr = &influxql.VarRef{}
sorted = opt.MergeSorted()
if !sorted {
t.Error("expected expression with varref to be sorted, got unsorted")
}
opt.Expr = &influxql.Call{}
sorted = opt.MergeSorted()
if sorted {
t.Error("expected expression without varref to be unsorted, got sorted")
}
}
// 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 {
inputs := make([]influxql.Iterator, 0, len(t.SeriesKeys))
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]) {
conditionFields[fields] = f
fields++
}
}
input, err := e.createVarRefSeriesIterator(ref, mm, seriesKey, t, t.Filters[i], conditionFields[:fields], opt)
if err != nil {
return err
} else if input == nil {
continue
}
inputs = append(inputs, input)
}
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
}