// expandWildcards returns a new SelectStatement with wildcards in the fields
// and/or GROUP BY exapnded with actual field names.
func (q *QueryExecutor) expandWildcards(stmt *influxql.SelectStatement) (*influxql.SelectStatement, error) {
// If there are no wildcards in the statement, return it as-is.
if !stmt.HasWildcard() {
return stmt, nil
}
// Use sets to avoid duplicate field names.
fieldSet := map[string]struct{}{}
dimensionSet := map[string]struct{}{}
var fields influxql.Fields
var dimensions influxql.Dimensions
// Iterate measurements in the FROM clause getting the fields & dimensions for each.
for _, src := range stmt.Sources {
if m, ok := src.(*influxql.Measurement); ok {
// Lookup the database. The database may not exist if no data for this database
// was ever written to the shard.
db := q.store.DatabaseIndex(m.Database)
if db == nil {
return stmt, nil
}
// Lookup the measurement in the database.
mm := db.measurements[m.Name]
if mm == nil {
return nil, ErrMeasurementNotFound(m.String())
}
// Get the fields for this measurement.
for _, name := range mm.FieldNames() {
if _, ok := fieldSet[name]; ok {
continue
}
fieldSet[name] = struct{}{}
fields = append(fields, &influxql.Field{Expr: &influxql.VarRef{Val: name}})
}
// Get the dimensions for this measurement.
for _, t := range mm.TagKeys() {
if _, ok := dimensionSet[t]; ok {
continue
}
dimensionSet[t] = struct{}{}
dimensions = append(dimensions, &influxql.Dimension{Expr: &influxql.VarRef{Val: t}})
}
}
}
// Return a new SelectStatement with the wild cards rewritten.
return stmt.RewriteWildcards(fields, dimensions), nil
}
// expandWildcards returns a new SelectStatement with wildcards in the fields
// and/or GROUP BY expanded with actual field names.
func (lm *LocalMapper) expandWildcards(stmt *influxql.SelectStatement) (*influxql.SelectStatement, error) {
// If there are no wildcards in the statement, return it as-is.
if !stmt.HasWildcard() {
return stmt, nil
}
// Use sets to avoid duplicate field names.
fieldSet := map[string]struct{}{}
dimensionSet := map[string]struct{}{}
var fields influxql.Fields
var dimensions influxql.Dimensions
// Iterate measurements in the FROM clause getting the fields & dimensions for each.
for _, src := range stmt.Sources {
if m, ok := src.(*influxql.Measurement); ok {
// Lookup the measurement in the database.
mm := lm.shard.index.Measurement(m.Name)
if mm == nil {
// This shard have never received data for the measurement. No Mapper
// required.
return stmt, nil
}
// Get the fields for this measurement.
for _, name := range mm.FieldNames() {
if _, ok := fieldSet[name]; ok {
continue
}
fieldSet[name] = struct{}{}
fields = append(fields, &influxql.Field{Expr: &influxql.VarRef{Val: name}})
}
// Get the dimensions for this measurement.
for _, t := range mm.TagKeys() {
if _, ok := dimensionSet[t]; ok {
continue
}
dimensionSet[t] = struct{}{}
dimensions = append(dimensions, &influxql.Dimension{Expr: &influxql.VarRef{Val: t}})
}
}
}
// Return a new SelectStatement with the wild cards rewritten.
return stmt.RewriteWildcards(fields, dimensions), nil
}
// rewriteSelectStatement performs any necessary query re-writing.
func (q *QueryExecutor) rewriteSelectStatement(stmt *influxql.SelectStatement) (*influxql.SelectStatement, error) {
var err error
// Expand regex expressions in the FROM clause.
sources, err := q.expandSources(stmt.Sources)
if err != nil {
return nil, err
}
stmt.Sources = sources
// Expand wildcards in the fields or GROUP BY.
if stmt.HasWildcard() {
stmt, err = q.expandWildcards(stmt)
if err != nil {
return nil, err
}
}
stmt.RewriteDistinct()
return stmt, nil
}