1. A method, comprising: sending to each of a plurality of segments to which a corresponding assigned portion of a query plan is assigned an associated transaction-related metadata, wherein the transaction-related metadata sent to each of the plurality of segments is associated with the corresponding assigned portion of the query plan assigned to the corresponding one of the plurality of segments and is determined to be used by a corresponding one of the plurality of segments to process the corresponding assigned portion of the query plan; receiving from zero or more of the plurality of segments a corresponding metadata modification record reflecting changes, if any, to system metadata required to be made to reflect changes to data made by that segment in processing the portion of the query plan assigned to that segment; determining whether the corresponding metadata modification record has been received from each of the of segments in the plurality of segments; in the event the corresponding metadata modification record is determined to have been received from each of the segments in the plurality of segments, updating a system metadata store to reflect the corresponding metadata modification records received from the plurality of segments, wherein the updating of the system metadata store comprises: replaying, by a master node, the corresponding metadata modification records received from each of the plurality of segments; and committing, by the master node, a transaction with which the query plan is associated, wherein the transaction is committed in response to determining that all of the plurality of segments to which a corresponding portion of the query plan is assigned have successfully completed the corresponding assigned portion for the query plan; and in the event that one or more of the plurality of segments fail to successfully complete the corresponding assigned portion of the query plan, aborting the transaction with which the query plan is associated.