through 3.0.0-beta.1-40 allowed read skew and lost updates by default, thanks to two auto-retry mechanisms which blindly re-applied updates when a transaction conflicted. TiDB also supports a select .. durability & fault tolerance in fresh clusters, and several crashes on startup. With both auto-retry mechanisms disabled, TiDB 2.1.8 through 3.0.0-beta.1-40 passed our tests for snapshot iso- lation and single-key a transactional SQL layer which stores data in TiKV Placement Driver is replicated via the Raft consensus algorithm for fault tolerance. Likewise, each TiKV shard is replicated with Raft, and stores data

implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures of the TiDB cluster and reduces the load of the leader. It contains a series of load balancing mechanisms that offload TiKV read loads from the leader replica to the follower replica in a Region. TiKV’s distributed consensus algorithm. Using this algorithm, both PD and TiKV, among components of the TiDB cluster, achieve disaster recovery of data, which is imple- mented through the following mechanisms: • The

of the TiDB cluster and reduces the load of the leader. It contains a series of load balancing mechanisms that offload TiKV read loads from the leader replica to the follower replica in a Region. TiKV’s distributed consensus algorithm. Using this algorithm, both PD and TiKV, among components of the TiDB cluster, achieve disaster recovery of data, which is imple- mented through the following mechanisms: • The its implementation principles. It is recommended that you learn some of the basic mechanisms, including the Raft consensus algorithm, dis- tributed transactions, data sharding, load balancing, the mapping

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 139 4.1.2 TiDB transaction mechanisms · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 139 4.1.3 The way applications implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures TiDB and TiDB Cloud, refer to the free online course Introduction to TiDB. 4.1.2 TiDB transaction mechanisms TiDB supports distributed transactions and offers both optimistic transaction and pes- simistic

implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures of the TiDB cluster and reduces the load of the leader. It contains a series of load balancing mechanisms that offload TiKV read loads from the leader replica to the follower replica in a Region. TiKV’s distributed consensus algorithm. Using this algorithm, both PD and TiKV, among components of the TiDB cluster, achieve disaster recovery of data, which is imple- mented through the following mechanisms: • The

range through a session variable TiDB is a multi-replica distributed database based on the Raft consensus algorithm. In face of high-concurrency and high-throughput application scenarios, TiDB can scale implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures of the TiDB cluster and reduces the load of the leader. It contains a series of load balancing mechanisms that offload TiKV read loads from the leader replica to the follower replica in a Region. TiKV’s

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 132 4.1.2 TiDB transaction mechanisms · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 132 4.1.3 The way applications implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures TiDB and TiDB Cloud, refer to the free online course Introduction to TiDB. 4.1.2 TiDB transaction mechanisms TiDB supports distributed transactions and offers both optimistic transaction and pes- simistic

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 126 4.1.2 TiDB transaction mechanisms · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 126 4.1.3 The way applications implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures TiDB and TiDB Cloud, refer to the free online course Introduction to TiDB. 4.1.2 TiDB transaction mechanisms TiDB supports distributed transactions and offers both optimistic transaction and pes- simistic

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 113 4.1.2 TiDB transaction mechanisms · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 113 4.1.3 The way applications implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures TiDB and TiDB Cloud, refer to the free online course Introduction to TiDB. 4.1.2 TiDB transaction mechanisms TiDB supports distributed transactions and offers both optimistic transaction and pes- simistic

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 133 4.1.2 TiDB transaction mechanisms · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 133 4.1.3 The way applications implementation of the Raft consensus algorithm. As a columnar storage extension of TiKV, TiFlash repli- cates data from TiKV in real time according to the Raft Learner consensus algorithm, which ensures TiDB and TiDB Cloud, refer to the free online course Introduction to TiDB. 4.1.2 TiDB transaction mechanisms TiDB supports distributed transactions and offers both optimistic transaction and pes- simistic