func Filter(query *parser.SelectQuery, series *protocol.Series) (*protocol.Series, error) {
if query.GetWhereCondition() == nil {
return series, nil
}
columns := map[string]struct{}{}
if query.GetFromClause().Type == parser.FromClauseInnerJoin {
outer:
for t, cs := range query.GetResultColumns() {
for _, c := range cs {
// if this is a wildcard select, then drop all columns and
// just use '*'
if c == "*" {
columns = make(map[string]struct{}, 1)
columns[c] = struct{}{}
break outer
}
columns[t.Name+"."+c] = struct{}{}
}
}
} else {
for _, cs := range query.GetResultColumns() {
for _, c := range cs {
columns[c] = struct{}{}
}
}
}
points := series.Points
series.Points = nil
for _, point := range points {
ok, err := matches(query.GetWhereCondition(), series.Fields, point)
if err != nil {
return nil, err
}
if ok {
filterColumns(columns, series.Fields, point)
series.Points = append(series.Points, point)
}
}
if _, ok := columns["*"]; !ok {
newFields := []string{}
for _, f := range series.Fields {
if _, ok := columns[f]; !ok {
continue
}
newFields = append(newFields, f)
}
series.Fields = newFields
}
return series, nil
}