example flow may proceed to s 790 if it is determined to roll back the transaction associated with delta object 870 accordingly a bit of the delta object map corresponding to the transaction is reset at s 790 and flow returns to s 730 accordingly and as shown in fig8 b a least significant bit of object map 840 is reset so as to no longer indicate the existence of delta object 870 fig9 is a flow diagram of process 900 for using the above described primitives to synchronize operations according to some embodiments process 900 involves three different types of locks a shared sub lock ssl an exclusive sub lock esl and a partial sub lock psl a transaction may be required to acquire an ssl in order to change an object and an esl to delete an object a transaction may acquire a psl in order to merge delta objects into an associated master object this merging may be used to reduce a number of persistent objects in object containers 252 according to some embodiments a transaction attempts to obtain a psl and merge delta objects prior to attempting to obtain a lock associated with a desired read write or delete operation a request to lock an object is received at s.