func (this *builder) VisitKeyspaceTerm(node *algebra.KeyspaceTerm) (interface{}, error) {
node.SetDefaultNamespace(this.namespace)
keyspace, err := this.getTermKeyspace(node)
if err != nil {
return nil, err
}
if node.Keys() != nil {
scan := NewKeyScan(node.Keys())
this.children = append(this.children, scan)
} else {
if this.subquery {
return nil, errors.NewError(nil, fmt.Sprintf(
"FROM in subquery must use KEYS clause: FROM %s.",
node.Keyspace()))
}
scan, err := this.selectScan(keyspace, node)
if err != nil {
return nil, err
}
this.children = append(this.children, scan)
}
fetch := NewFetch(keyspace, node)
this.subChildren = append(this.subChildren, fetch)
return nil, nil
}
func (this *builder) getTermKeyspace(node *algebra.KeyspaceTerm) (datastore.Keyspace, error) {
node.SetDefaultNamespace(this.namespace)
ns := node.Namespace()
datastore := this.datastore
if strings.ToLower(ns) == "#system" {
datastore = this.systemstore
}
namespace, err := datastore.NamespaceByName(ns)
if err != nil {
return nil, err
}
keyspace, err := namespace.KeyspaceByName(node.Keyspace())
if err != nil {
return nil, err
}
return keyspace, nil
}
func (this *builder) selectScan(keyspace datastore.Keyspace,
node *algebra.KeyspaceTerm) (Operator, error) {
if this.where == nil {
return this.selectPrimaryScan(keyspace, node)
}
nnf := planner.NewNNF()
where := this.where.Copy()
where, err := nnf.Map(where)
if err != nil {
return nil, err
}
formalizer := expression.NewFormalizer()
formalizer.Keyspace = node.Alias()
primaryKey := expression.NewField(
expression.NewMeta(expression.NewConstant(node.Alias())),
expression.NewFieldName("id"))
indexers, err := keyspace.Indexers()
if err != nil {
return nil, err
}
indexes := make([]datastore.Index, 0, len(indexers)*16)
primaryIndexes := make(map[datastore.Index]bool, len(indexers)*2)
for _, indexer := range indexers {
idxs, err := indexer.Indexes()
if err != nil {
return nil, err
}
indexes = append(indexes, idxs...)
primaryIdxs, err := indexer.PrimaryIndexes()
if err != nil {
return nil, err
}
for _, p := range primaryIdxs {
primaryIndexes[p] = true
}
}
unfiltered := make(map[datastore.Index]expression.Expression, len(indexes))
filtered := make(map[datastore.Index]expression.Expression, len(indexes))
for _, index := range indexes {
state, _, er := index.State()
if er != nil {
return nil, er
}
if state != datastore.ONLINE {
continue
}
var key expression.Expression
if primaryIndexes[index] {
key = primaryKey
} else {
rangeKey := index.RangeKey()
if len(rangeKey) == 0 || rangeKey[0] == nil {
// Index not rangeable
continue
}
key := rangeKey[0].Copy()
key, err = formalizer.Map(key)
if err != nil {
return nil, err
}
key, err = nnf.Map(key)
if err != nil {
return nil, err
}
}
if !planner.SargableFor(where, key) {
// Index not applicable
continue
}
indexCond := index.Condition()
if indexCond == nil {
unfiltered[index] = key
continue
}
indexCond = indexCond.Copy()
indexCond, err = formalizer.Map(indexCond)
if err != nil {
return nil, err
}
indexCond, err = nnf.Map(indexCond)
if err != nil {
return nil, err
}
if planner.SubsetOf(where, indexCond) {
// Index condition satisfies query condition
filtered[index] = key
break
}
}
var indexMap map[datastore.Index]expression.Expression
if len(filtered) > 0 {
indexMap = filtered
} else if len(unfiltered) > 0 {
indexMap = unfiltered
}
for index, key := range indexMap {
spans := planner.SargFor(where, key)
var scan Operator
scan = NewIndexScan(index, node, spans, false, math.MaxInt64)
if len(spans) > 1 {
// Use UnionScan to de-dup multiple spans
scan = NewUnionScan(scan)
}
return scan, err
}
return this.selectPrimaryScan(keyspace, node)
}