MySQL Cluster by Ralf Gebhardt

Ralf Gebhardt of SkySQL.

Cluster: shared nothing architecture (no single point of failure), synchronous replication between nodes, ACID transactions, row level locking. In-memory storage (some data can be stored on disk, but indexes must be in-memory). Checkpointing to disk for durability. It supports two types of indexes – ordered T-trees, unique hash indexes. Online operations like adding node groups, software upgrades, table alterations. Quick standard architecture diagram displayed about MySQL Cluster.

Network partitioning protocol is designed to avoid a split brain scenario. Is there at least one node from each node group? If not then this part cannot continue – graceful shutdown. Are all nodes present from any node group? If so, then this is the only viable cluster – continue to operate. Ask the arbitrator – the arbitrator which parts will continue if no arbitrator is available the cluster shuts down.

Durability – in order for a node to recover fast some data is stored locally. The REDO log is synchronized by global checkpoints (GCP). The DataMemory is synchronized by local checkpoints (LCP).

I agree with Ralf — almost impossible to talk about NDB in 25 minutes. Its very deep, you’d need at least three hours to grasp it well.