SYSTEM AND METHOD FOR CREATING A DISTRIBUTED TRANSACTION MANAGER SUPPORTING REPEATABLE READ ISOLATION LEVEL IN A MPP DATABASE

摘要

Embodiments are provided to provide a distributed transaction manager supporting repeatable read isolation level in Massively Parallel Processing (MPP) database systems without a centralized component. Before starting a transaction, a first node identifies a second node involved in the transaction, and requests from the second node a snapshot of current transactions at the second node. After receiving the snapshot from the second node, the first node combines into a reconciled snapshot the snapshot of transactions from the second node with current transactions at the first node. The first node then transmits the reconciled snapshot to the second node and starts the transaction using the reconciled snapshot. A branch transaction is then started at the second node in accordance with the reconciled snapshot. Upon ending the transaction and the branch transaction, the first node and the second node perform a two phase commit (2PC) protocol.