Disclosed herein is a data synchronization between a client computing device's local store and another data store, such as a data store that is remote to the client computing device. The other data store may comprise a cloud data store. The existence, or absence, of a causal relationship between the local and remote data stores for a given data item is used to determine whether or not a conflict exists and/or whether a requested operation may be performed. The causal relationship may be determined using a previous commit's hash value, referred to as a hash_base value, and a hash value, both of which are associated with the data item.