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)
}
