XAP
XAP is a distributed in-memory data grid that has high throughput and low latency due to storing all data in memory. As a result, there is no transaction delay between physical I/O so XAP can be applied to distributed applications ranging from financial services to retail. XAP has 3 tiers to its services: Open source, Premium, and Enterprise. The open source edition supports data partitioning, event processing, and distributed execution. It also supports full transactionality by maintaining full ACID compliance.
History
XAP is owned by GigaSpaces, which is an Israeli software company founded in 2000 by Nati Shalom. It was designed to be used to speed up performance or scalability of many existing database systems such as MySQL or MongoDB. XAP has many similarities to NoSQL with regards to the architecture such as using a scale-out model for scalability.
Logging
All transactions are logged to a redo log. A primary node logs all the transactions into this log and if a backup node goes down, all the data gets replayed to a new backup that is created through a recovery process. Essentially, the redo log keeps all events that need to be replicated until the primary node re-establishes a connection with the backup. The redo log can be configured in from the max capacity to the buffer size that is being used to flush packets to disk.
