This doesn't sync, so call this only when you don't care about dirty posting lists in memory(for example before populating snapshot) or after calling syncAllMarks.

Get stores the List corresponding to key, if it's not there already.

GetNoStore takes a key.

Init initializes the posting lists package, the in memory and dirty list hash.

RebuildIndex rebuilds index for a given attribute.

RebuildReverseEdges rebuilds the reverse edges for a given attribute.

TypeID returns the typeid of destination vertex.

Copies the val if it's uid only posting, be careful.

Add means add new element in mutation layer.

Del means delete in mutation layer.

Set means overwrite in mutation layer.

ErrNoValue would be returned if no value was found in the posting list.

ErrRetry can be triggered if the posting list got deleted from memory due to a hard commit.

ListOptions is used in List.Uids (in posting) to customize our output list of UIDs, for each posting list.