130 lines
3.7 KiB
Go
130 lines
3.7 KiB
Go
package influxql
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type subqueryBuilder struct {
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ic IteratorCreator
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stmt *SelectStatement
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}
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// buildAuxIterator constructs an auxiliary Iterator from a subquery.
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func (b *subqueryBuilder) buildAuxIterator(opt IteratorOptions) (Iterator, error) {
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// Retrieve a list of fields needed for conditions.
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auxFields := opt.Aux
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conds := ExprNames(opt.Condition)
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if len(conds) > 0 {
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auxFields = make([]VarRef, len(opt.Aux)+len(conds))
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copy(auxFields, opt.Aux)
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copy(auxFields[len(opt.Aux):], conds)
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}
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// Map the desired auxiliary fields from the substatement.
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indexes := b.mapAuxFields(auxFields)
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subOpt, err := newIteratorOptionsSubstatement(b.stmt, opt)
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if err != nil {
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return nil, err
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}
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subOpt.Aux = auxFields
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itrs, err := buildIterators(b.stmt, b.ic, subOpt)
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if err != nil {
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return nil, err
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}
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// Construct the iterators for the subquery.
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input := NewIteratorMapper(itrs, nil, indexes, subOpt)
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// If there is a condition, filter it now.
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if opt.Condition != nil {
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input = NewFilterIterator(input, opt.Condition, subOpt)
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}
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return input, nil
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}
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func (b *subqueryBuilder) mapAuxFields(auxFields []VarRef) []IteratorMap {
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indexes := make([]IteratorMap, len(auxFields))
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for i, name := range auxFields {
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m := b.mapAuxField(&name)
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if m == nil {
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// If this field doesn't map to anything, use the NullMap so it
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// shows up as null.
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m = NullMap{}
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}
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indexes[i] = m
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}
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return indexes
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}
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func (b *subqueryBuilder) mapAuxField(name *VarRef) IteratorMap {
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offset := 0
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for i, f := range b.stmt.Fields {
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if f.Name() == name.Val {
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return FieldMap(i + offset)
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} else if call, ok := f.Expr.(*Call); ok && (call.Name == "top" || call.Name == "bottom") {
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// We may match one of the arguments in "top" or "bottom".
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if len(call.Args) > 2 {
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for j, arg := range call.Args[1 : len(call.Args)-1] {
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if arg, ok := arg.(*VarRef); ok && arg.Val == name.Val {
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return FieldMap(i + j + 1)
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}
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}
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// Increment the offset so we have the correct index for later fields.
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offset += len(call.Args) - 2
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}
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}
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}
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// Unable to find this in the list of fields.
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// Look within the dimensions and create a field if we find it.
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for _, d := range b.stmt.Dimensions {
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if d, ok := d.Expr.(*VarRef); ok && name.Val == d.Val {
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return TagMap(d.Val)
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}
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}
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// Unable to find any matches.
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return nil
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}
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func (b *subqueryBuilder) buildVarRefIterator(expr *VarRef, opt IteratorOptions) (Iterator, error) {
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// Look for the field or tag that is driving this query.
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driver := b.mapAuxField(expr)
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if driver == nil {
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// Exit immediately if there is no driver. If there is no driver, there
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// are no results. Period.
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return nil, nil
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}
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// Determine necessary auxiliary fields for this query.
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auxFields := opt.Aux
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conds := ExprNames(opt.Condition)
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if len(conds) > 0 && len(opt.Aux) > 0 {
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// Combine the auxiliary fields requested with the ones in the condition.
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auxFields = make([]VarRef, len(opt.Aux)+len(conds))
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copy(auxFields, opt.Aux)
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copy(auxFields[len(opt.Aux):], conds)
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} else if len(conds) > 0 {
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// Set the auxiliary fields to what is in the condition since we have
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// requested none in the query itself.
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auxFields = conds
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}
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// Map the auxiliary fields to their index in the subquery.
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indexes := b.mapAuxFields(auxFields)
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subOpt, err := newIteratorOptionsSubstatement(b.stmt, opt)
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if err != nil {
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return nil, err
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}
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subOpt.Aux = auxFields
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itrs, err := buildIterators(b.stmt, b.ic, subOpt)
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if err != nil {
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return nil, err
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}
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// Construct the iterators for the subquery.
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input := NewIteratorMapper(itrs, driver, indexes, subOpt)
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// If there is a condition, filter it now.
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if opt.Condition != nil {
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input = NewFilterIterator(input, opt.Condition, subOpt)
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}
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return input, nil
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}
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