24. The system of claim 16 , wherein the tag assignment module is further configured to detect satisfaction of a flush condition, when the flush condition is satisfied the tag assignment module performing a flush operation, including building a sorted map, the sorted map relating globally unique identifiers to document identification tags assigned to documents since a prior flush operation.
24. The system of claim 16 , wherein the tag assignment module is further configured to detect satisfaction of a flush condition, when the flush condition is satisfied the tag assignment module performing a flush operation, including building a sorted map, the sorted map relating globally unique identifiers to document identification tags assigned to documents since a prior flush operation. 25. The system of claim 24 , wherein the tag assignment module is further configured to detect satisfaction of a merge condition, when the merge condition is satisfied the tag assignment module performing a merge operation, the merge operation including merging a plurality of sorted maps produced by previous flushing operations, the merge operation further including producing a merged map relating globally unique identifiers to document identification tags assigned to documents.