func (qs *QuadStore) optimizeAndIterator(it *iterator.And) (graph.Iterator, bool) {
// Fail fast if nothing can happen
glog.V(4).Infoln("Entering optimizeAndIterator", it.UID())
found := false
for _, it := range it.SubIterators() {
glog.V(4).Infoln(it.Type())
if it.Type() == mongoType {
found = true
}
}
if !found {
glog.V(4).Infoln("Aborting optimizeAndIterator")
return it, false
}
newAnd := iterator.NewAnd(qs)
var mongoIt *Iterator
for _, it := range it.SubIterators() {
switch it.Type() {
case mongoType:
if mongoIt == nil {
mongoIt = it.(*Iterator)
} else {
newAnd.AddSubIterator(it)
}
case graph.LinksTo:
continue
default:
newAnd.AddSubIterator(it)
}
}
stats := mongoIt.Stats()
lset := []graph.Linkage{
{
Dir: mongoIt.dir,
Value: mongoIt.hash,
},
}
n := 0
for _, it := range it.SubIterators() {
if it.Type() == graph.LinksTo {
lto := it.(*iterator.LinksTo)
// Is it more effective to do the replacement, or let the mongo check the linksto?
ltostats := lto.Stats()
if (ltostats.ContainsCost+stats.NextCost)*stats.Size > (ltostats.NextCost+stats.ContainsCost)*ltostats.Size {
continue
}
newLto := NewLinksTo(qs, lto.SubIterators()[0], "quads", lto.Direction(), lset)
newAnd.AddSubIterator(newLto)
n++
}
}
if n == 0 {
return it, false
}
return newAnd.Optimize()
}
func (qs *QuadStore) optimizeAnd(it *iterator.And) (graph.Iterator, bool) {
subs := it.SubIterators()
var unusedIts []graph.Iterator
var newit *SQLIterator
newit = nil
changed := false
var err error
for _, it := range subs {
if it.Type() == sqlType {
if newit == nil {
newit = it.(*SQLIterator)
} else {
changed = true
newit, err = intersect(newit.sql, it.(*SQLIterator).sql, qs)
if err != nil {
glog.Error(err)
return it, false
}
}
} else {
unusedIts = append(unusedIts, it)
}
}
if !changed {
return it, false
}
if len(unusedIts) == 0 {
newit.Tagger().CopyFrom(it)
return newit, true
}
newAnd := iterator.NewAnd(qs)
newAnd.Tagger().CopyFrom(it)
newAnd.AddSubIterator(newit)
for _, i := range unusedIts {
newAnd.AddSubIterator(i)
}
return newAnd.Optimize()
}