A system, comprising: a plurality of storage nodes (1020, 1030), comprising a processor and a memory, that store respective versions of a hierarchical data structure consistent with a transaction log for the hierarchical data structure; a transaction log store, that maintains a transaction log for the hierarchical data structure; a client device; one of the storage nodes, configured to: receive a request issued from the client device to commit a transaction to a hierarchical data structure that includes a transaction state token, the transaction state token generated by the client device from transaction state information received by the client device from another one of the plurality of storage nodes, the transaction state information formed by the another one of the plurality of storage nodes on performing one or more prior operations requested by the client device, wherein the request to commit the transaction includes one or more additional operations to perform by the one storage node as part of the transaction; generate a conflict validation request for the transaction including the one or more prior operations and the one or more additional operations and send the conflict validation request to the transaction log store; and responsive to determining that the transaction does not conflict based on the conflict validation received from transaction log store, perform the one or more additional operations on a version of the hierarchical data structure stored at the one storage node and return a response to the request to the client device acknowledging that the transaction has been committed to the hierarchical data structure. a plurality of storage nodes (1020, 1030), comprising a processor and a memory, that store respective versions of a hierarchical data structure consistent with a transaction log for the hierarchical data structure; a transaction log store, that maintains a transaction log for the hierarchical data structure; a client device; one of the storage nodes, configured to: receive a request issued from the client device to commit a transaction to a hierarchical data structure that includes a transaction state token, the transaction state token generated by the client device from transaction state information received by the client device from another one of the plurality of storage nodes, the transaction state information formed by the another one of the plurality of storage nodes on performing one or more prior operations requested by the client device, wherein the request to commit the transaction includes one or more additional operations to perform by the one storage node as part of the transaction; generate a conflict validation request for the transaction including the one or more prior operations and the one or more additional operations and send the conflict validation request to the transaction log store; and responsive to determining that the transaction does not conflict based on the conflict validation received from transaction log store, perform the one or more additional operations on a version of the hierarchical data structure stored at the one storage node and return a response to the request to the client device acknowledging that the transaction has been committed to the hierarchical data structure. receive a request issued from the client device to commit a transaction to a hierarchical data structure that includes a transaction state token, the transaction state token generated by the client device from transaction state information received by the client device from another one of the plurality of storage nodes, the transaction state information formed by the another one of the plurality of storage nodes on performing one or more prior operations requested by the client device, wherein the request to commit the transaction includes one or more additional operations to perform by the one storage node as part of the transaction; generate a conflict validation request for the transaction including the one or more prior operations and the one or more additional operations and send the conflict validation request to the transaction log store; and responsive to determining that the transaction does not conflict based on the conflict validation received from transaction log store, perform the one or more additional operations on a version of the hierarchical data structure stored at the one storage node and return a response to the request to the client device acknowledging that the transaction has been committed to the hierarchical data structure.