// SelectTags returns a list of non-field tags in the SELECT section of stmt.
func (m *Measurement) SelectTags(stmt *influxql.SelectStatement) []string {
set := newStringSet()
for _, name := range stmt.NamesInSelect() {
if !m.HasField(name) && m.HasTagKey(name) {
set.add(name)
}
}
return set.list()
}
// SelectFields returns a list of fields in the SELECT section of stmt.
func (m *Measurement) SelectFields(stmt *influxql.SelectStatement) []string {
set := newStringSet()
for _, name := range stmt.NamesInSelect() {
if m.HasField(name) {
set.add(name)
continue
}
}
return set.list()
}
// createTagSetsAndFields returns the tagsets and various fields given a measurement and
// SELECT statement.
func createTagSetsAndFields(m *Measurement, stmt *influxql.SelectStatement) (*tagSetsAndFields, error) {
_, tagKeys, err := stmt.Dimensions.Normalize()
if err != nil {
return nil, err
}
sfs := newStringSet()
sts := newStringSet()
wfs := newStringSet()
// Validate the fields and tags asked for exist and keep track of which are in the select vs the where
for _, n := range stmt.NamesInSelect() {
if m.HasField(n) {
sfs.add(n)
continue
}
if m.HasTagKey(n) {
sts.add(n)
}
}
for _, n := range stmt.NamesInDimension() {
if m.HasTagKey(n) {
tagKeys = append(tagKeys, n)
}
}
for _, n := range stmt.NamesInWhere() {
if n == "time" {
continue
}
if m.HasField(n) {
wfs.add(n)
continue
}
}
// Get the sorted unique tag sets for this statement.
tagSets, err := m.TagSets(stmt, tagKeys)
if err != nil {
return nil, err
}
return &tagSetsAndFields{
tagSets: tagSets,
selectFields: sfs.list(),
selectTags: sts.list(),
whereFields: wfs.list(),
}, nil
}