Fixed comments

posting/list_test.go

@@ -480,7 +480,6 @@ func TestReadSingleValue(t *testing.T) {
  require.NoError(t, err)
  checkValue(t, ol, string(k.Postings[0].Value), uint64(j))
  }
-
  }
 }
 

posting/lists.go

@@ -195,24 +195,35 @@ func (lc *LocalCache) getInternal(key []byte, readFromDisk bool) (*List, error)
  return lc.SetIfAbsent(skey, pl), nil
 }
 
+// GetSinglePosting retrieves the cached version of the first item in the list associated with the
+// given key. This is used for retrieving the value of a scalar predicats.
 func (lc *LocalCache) GetSinglePosting(key []byte) (*pb.PostingList, error) {
+ getDeltas := func() *pb.PostingList {
+ lc.RLock()
+ defer lc.RUnlock()
 
- getPostings := func() (*pb.PostingList, error) {
  pl := &pb.PostingList{}
- lc.RLock()
  if delta, ok := lc.deltas[string(key)]; ok && len(delta) > 0 {
  err := pl.Unmarshal(delta)
  if err != nil {
- lc.RUnlock()
- return pl, nil
+ return pl
  }
  }
- lc.RUnlock()
 
+ return nil
+ }
+
+ getPostings := func() (*pb.PostingList, error) {
+ pl := getDeltas()
+ if pl != nil {
+ return pl, nil
+ }
+
+ pl = &pb.PostingList{}
  txn := pstore.NewTransactionAt(lc.startTs, false)
  item, err := txn.Get(key)
  if err != nil {
- return pl, err
+ return nil, err
  }
 
  err = item.Value(func(val []byte) error {
@@ -227,10 +238,10 @@ func (lc *LocalCache) GetSinglePosting(key []byte) (*pb.PostingList, error) {
 
  pl, err := getPostings()
  if err == badger.ErrKeyNotFound {
- err = nil
+ return nil, nil
  }
  if err != nil {
- return pl, err
+ return nil, err
  }
 
  // Filter and remove STAR_ALL and OP_DELETE Postings

worker/task.go

@@ -376,9 +376,14 @@ func (qs *queryState) handleValuePostings(ctx context.Context, args funcArgs) er
 
  outputs := make([]*pb.Result, numGo)
  listType := schema.State().IsList(q.Attr)
+
+ // These are certain special cases where we can get away with reading only the latest value
+ // Lang doesn't work because we would be storing various different languages at various
+ // time. So when we go to read the latest value, we might get a different language.
+ // Similarly with DoCount and ExpandAll and Facets. List types are also not supported
+ // because list is stored by time, and we combine all the list items at various timestamps.
  hasLang := schema.State().HasLang(q.Attr)
- getMultiplePosting := q.DoCount || q.ExpandAll || listType || hasLang
- //getMultiplePosting := true
+ getMultiplePosting := q.DoCount || q.ExpandAll || listType || hasLang || q.FacetParam != nil
 
  calculate := func(start, end int) error {
  x.AssertTrue(start%width == 0)
@@ -399,7 +404,10 @@ func (qs *queryState) handleValuePostings(ctx context.Context, args funcArgs) er
  fcs := &pb.FacetsList{FacetsList: make([]*pb.Facets, 0)} // TODO Figure out how it is stored
 
  if !getMultiplePosting {
- pl, _ := qs.cache.GetSinglePosting(key)
+ pl, err := qs.cache.GetSinglePosting(key)
+ if err != nil {
+ return err
+ }
  if pl == nil || len(pl.Postings) == 0 {
  out.UidMatrix = append(out.UidMatrix, &pb.List{})
  out.FacetMatrix = append(out.FacetMatrix, &pb.FacetsList{})
@@ -413,11 +421,6 @@ func (qs *queryState) handleValuePostings(ctx context.Context, args funcArgs) er
  Tid: types.TypeID(p.ValType),
  Value: p.Value,
  }
-
- // TODO Apply facet tree before
- if q.FacetParam != nil {
- fcs.FacetsList = append(fcs.FacetsList, &pb.Facets{Facets: facets.CopyFacets(p.Facets, q.FacetParam)})
- }
  }
  } else {
  pl, err := qs.cache.Get(key)