The second rule ensures that two write operations from two transactions cannot occur concurrently on the same data item. Additionally, it ensures that a read quorum contains at least one site with the newest version of the data item. The first rule ensures that a data item is not read and written by two transactions concurrently. Then the following rules must be obeyed in the implementation of the commit protocol: Let us assume that the total number of votes in the system is V and the abort and commit quorums are V a and V c, respectively. The fundamental idea is that a transaction is executed if the majority of sites vote to execute it.Įvery site in the system is assigned a vote V i. In a distributed database system, a transaction could execute its operations at multiple sites. Quorum-based voting can be used as a replica control method, as well as a commit method to ensure transaction atomicity in the presence of network partitioning. This is where a quorum-based technique comes in. Quorum-based techniques in distributed database systems. In case of network partitioning, sites are partitioned and the partitions may not be able to communicate with each other. Older-me had often thought of it as a magical superpower assigned to most of the human race whose delivery envelope with his name on it had gone. Since atomicity requires every distributed transaction to be atomic, the transaction must have the same fate ( commit or abort) at every site. One of the key points that made me so bone-deep certain that me-me was different from older-me was social perception. Quorum-based voting can be used as a replica control method, Īs well as a commit method to ensure transaction atomicity in the presence of network partitioning. Quorum-based techniques in distributed database systems 1.2 Quorum-based voting for replica control.1.1 Quorum-based voting in commit protocols.1 Quorum-based techniques in distributed database systems.